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Crystals
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Optoelectronics and Photonics in Crystals
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Optoelectronics and Photonics in Crystals

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Materials for Energy Applications".

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 37638

Special Issue Editors

Prof. Dr. Fu-Der Lai

E-Mail Website
Guest Editor
Institute of Photonics Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 824005, Taiwan
Interests: optoelectronics; photonics; nano semiconductor; solar absorber; LED
Prof. Dr. Mu-Chun Wang

E-Mail Website
Guest Editor
Department of Electronic Engineering, MingHsin University of Science and Technology, Hsinchu 304, Taiwan
Interests: fiber-optic sensors; VLSI/nano-node process integration; nano-Si device design; semiconductor physics
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Wen-Ching Hsieh

E-Mail Website
Guest Editor
Opto-Electronic System Engineering Department, Minghsin University of Science and Technology, Xinfeng 30401, Taiwan
Interests: photoelectric conversion (such as sensors, detectors, solar cells, etc.)

Special Issue Information

Dear Colleagues,

Whether viable at present or in the future, 5G communication, the Metaverse, AI control, autonomous driving, etc., are already mainstream technologies. These products all require optoelectronic components, and the quality of these optoelectronic components depends on the optoelectronic or optical properties of the materials or devices. Therefore, this Special Issue will focus on Optoelectronics and Photonics in Crystals.

Requirements for submission:

Manufacturing (including crystal growth, epitaxy processes, coating, etc.), simulation (including theory, computational process, modeling, etc.), analysis and application of materials or devices with their photoelectric characteristics including photoelectric conversion (such as in sensors, detectors, solar cells, etc.), electro-optical conversion (such as illuminators, LEDs, Lasers, etc.) and other photoelectric or optical characteristics (such as photoluminescence, etc.). An improvement in performance and efficiency is required.

Material type: Semiconductor, polymer, composite, organic, ceramic, etc.

Material form: Buck, epitaxial, thin film with ordered structures, etc.

Crystal type: Crystal, polycrystal, nanocrystal, quasicrystal, liquid crystal, etc.

Reviews and brief research reports are also included.

Prof. Dr. Fu-Der Lai
Prof. Dr. Mu-Chun Wang
Prof. Dr. Wen-Ching Hsieh
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • optoelectronics
  • photonics
  • optics
  • photoelectric conversion
  • electro-optical conversion

Published Papers (21 papers)

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20 pages, 8540 KiB  
Article
Enhancing the Tunable Sensitivity of a Near-Ultraviolet to Visible to Near-Infrared Photo Irradiance Sensor Using an Indium Tin Oxide-Aluminum Oxide-Zirconia Aluminum Oxide-Silicon
by Wen-Ching Hsieh, Bing-Mau Chen, Mu-Chun Wang, Yih-Shing Lee and Chien-Chung Tsai
Crystals 2023, 13(11), 1530; https://doi.org/10.3390/cryst13111530 - 24 Oct 2023
Viewed by 781
Abstract
This study focuses on enhancing the tunable sensitivity of a photo irradiance sensor (PIS) operating in the near-ultraviolet to visible to near-infrared (NUV-VIS-NIR) spectrum using an indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon capacitor (hereafter IAZAOS). Unlike other PIS designs such as reverse-biased [...] Read more.
This study focuses on enhancing the tunable sensitivity of a photo irradiance sensor (PIS) operating in the near-ultraviolet to visible to near-infrared (NUV-VIS-NIR) spectrum using an indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon capacitor (hereafter IAZAOS). Unlike other PIS designs such as reverse-biased metal–insulator–semiconductor (MIS) and tunneling MIS, the IAZAOS PIS measures changes in inversion capacitance under strong forward bias with light irradiation. The IAZAOS PIS offers several key advantages over alternative designs. It exhibits high sensitivity, weak bias dependence, low dark current, tunable sensitivity, low power consumption, CMOS process compatibility, simple low-cost manufacturing, and good gate oxide reliability. Under 1 mW/cm2 irradiation at 1 kHz, the inversion carrier concentration reaches approximately 70% saturation. The resolution achieved is 10 nW/cm2 at 1 kHz, with a sensing range spanning from 10 nW/cm2 to 1 W/cm2 across frequencies from 1 kHz to 100 kHz. These performance characteristics surpass those reported for other PIS technologies. Furthermore, the IAZAOS PIS demonstrates a quantum efficiency of about 60% at 405 nm, which surpasses the quantum efficiency of general silicon-based p(i)n diodes. Post-deposition annealing techniques are employed to enhance the sensor’s performance. Dielectric annealing improves the ZrAlOx interface trap and permittivity properties, while conducting oxide annealing enhances indium tin oxide transmission and resistivity. The combination of these treatments results in a high-speed, high-sensitivity, high-resolution, and reliable NUV-VIS-NIR sensing capability for the IAZAOS capacitor-based PIS. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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13 pages, 5567 KiB  
Article
Effects of Oxygen Flows and Annealing Temperatures on Optical, Electrical, and Structural Properties of Co-Sputtered In2O3-Ga2O3-Zn Thin Films
by Yih-Shing Lee, Sheng-Yu Zhao, Yuan-Zhe Lin, Glen Andrew Porter and Tsung-Cheng Tien
Crystals 2023, 13(9), 1310; https://doi.org/10.3390/cryst13091310 - 28 Aug 2023
Viewed by 973
Abstract
This study investigated the effects of oxygen (O2) flow rates and annealing temperatures on optical, electrical, and structural properties of indium–gallium–zinc oxide (IGZO) film on glass substrates fabricated by using a co-sputtering system with two radio-frequency (RF) (In2O3 [...] Read more.
This study investigated the effects of oxygen (O2) flow rates and annealing temperatures on optical, electrical, and structural properties of indium–gallium–zinc oxide (IGZO) film on glass substrates fabricated by using a co-sputtering system with two radio-frequency (RF) (In2O3 and Ga2O3) and one direct current (DC) (Zn) magnetron. The average transmittance and optical energy gap increased significantly when the oxygen flow rate was increased from 1 sccm to 3 sccm. An increased O2 flow during co-sputtering IGZO films caused the crystallinity of the InGaZn7O10 phase to increase, yielding a smoother and more uniform granular structure. The carrier mobility rose and the carrier concentration decreased with increasing O2 flow. The results of X-ray photoelectron spectra (XPS) analyses explained the impacts of the O2 flow rates and annealing temperatures on optical and electrical properties of the co-sputtered IGZO films. The optimum process conditions of the co-sputtered In2O3-Ga2O3-Zn films were revealed as an O2 flow rate of 3 sccm and an annealing temperature at 300 °C, which showed the largest average transmittance of 82.48%, a larger optical bandgap of 3.21 eV, and a larger carrier mobility of 7.01 cm2 V−1s−1. XPS results at various annealing temperatures indicated that the co-sputtered IGZO films with an O2 flow rate of 3 sccm have more stable chemical compositions among different annealing temperatures. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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18 pages, 5943 KiB  
Article
Performance Comparison of SONOS-Type UV TD Sensor Using Indium Tin Oxide-Aluminum Oxide-Zirconia Aluminum Oxide-Silicon Oxide-Silicon and Indium Tin Oxide-Aluminum Oxide-Hafnium Aluminum Oxide-Silicon Oxide-Silicon
by Fun-Cheng Jong and Wen-Ching Hsieh
Crystals 2023, 13(7), 1092; https://doi.org/10.3390/cryst13071092 - 13 Jul 2023
Cited by 1 | Viewed by 802
Abstract
This study compares the performance of two types of capacitive devices, indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon (IAZAOS) and indium tin oxide-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon (IAHAOS), as silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory (NVM) total dose of ultraviolet radiation (UV TD) sensors. Results [...] Read more.
This study compares the performance of two types of capacitive devices, indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon (IAZAOS) and indium tin oxide-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon (IAHAOS), as silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory (NVM) total dose of ultraviolet radiation (UV TD) sensors. Results show that IAZAOS with zirconia aluminum oxide as the charge-trapping layer outperforms IAHAOS with hafnium aluminum oxide for a UV TD sensor. After exposure to UV TD irradiation of 100 mW·s/cm2, the threshold voltage (VT) change of IAZAOS is almost 1.25 times that of IAHAOS. The study also found that annealing can significantly improve the response performance of IAZAOS UV TD sensors. Furthermore, IAZAOS devices with partially smaller nanocrystals in the charge-trapping layer greatly enhance the response of SONOS-type UV TD sensors. The study also compared the constant voltage stress-induced leakage current (CVSILC) and found that the CVSILC for annealed IAZAOS devices is 1000 times smaller than that of IAHAOS devices. Moreover, the IAZAOS-I2Z2 exhibits a superior performance regarding irradiation/refresh cycle endurance as compared to the IAHAOS-I2H1 device. These findings suggest that IAZAOS capacitive devices have superior performance and potential for use in SONOS-type UV TD sensors. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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9 pages, 3781 KiB  
Article
Effect of Surface Texture on Light Extraction Efficiency for LEDs
by Fu-Der Lai
Crystals 2023, 13(3), 491; https://doi.org/10.3390/cryst13030491 - 12 Mar 2023
Viewed by 1335
Abstract
The light extraction efficiency of an LED is dependent on its surface texture. However, the surface of the p-GaN layer is not easy to be etch with inverted hexagonal pyramid structures (IHPS) with small top widths and large depths using existing methods. Therefore, [...] Read more.
The light extraction efficiency of an LED is dependent on its surface texture. However, the surface of the p-GaN layer is not easy to be etch with inverted hexagonal pyramid structures (IHPS) with small top widths and large depths using existing methods. Therefore, it is important to discuss the expected effect of the conditions of thermal annealing and inductively coupled plasma (ICP) reactive ion etching (RIE) for the generation of nano-pin-holes in the photoresist and fabrication of the top surface structure of GaN-based LEDs, in order to enhance the light output power. In this study, the following four items will be discussed: (1) the effect of thermal annealing on the composition of the photoresist; (2) the effect of thermal annealing and ICP RIE on the generation of the nano-pin-holes in the photoresist; (3) the effect of ICP RIE on the IHPS; and (4) the effect of surface texture of the IHPS on the light output power. It has been found that a nano-pin-hole structure in the photoresist etching mask is needed for the fabrication of many IHPS on the LED surface. A maskless via-hole etching technique was used for texturing the photoresist to produce nano-pore structures with diameters of less than 50 nm. The relationship between the light extraction efficiency and the surface texture is discussed in detail. The simulation results show the best light extraction efficiency (LEE) ratio of 358% to be obtained when the distance between two neighboring IHPS patterns (DBNP) is 300 nm. This in turn allowed the formation of IHPS with small top widths and large depths on the LED surface. A LEE ratio of 305% was obtained with the fabrication of IHPS with a top width of 290 nm, a depth of 170 nm and a DBNP of 180 nm on the LED surface. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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13 pages, 3102 KiB  
Article
Thickness Study of Ga2O3 Barrier Layer in p-Si/n-MgZnO:Er/Ga2O3/ZnO:In Diode
by Shih-Wei Ying, Shou-Yen Chao, Ming-Chang Shih, Chien-Jung Huang and Wen-How Lan
Crystals 2023, 13(2), 275; https://doi.org/10.3390/cryst13020275 - 05 Feb 2023
Viewed by 1185
Abstract
The p-Si/n-MgZnO:Er/Ga2O3/ZnO:In diodes with different Ga2O3 thicknesses were fabricated through spray pyrolysis deposition at 450 °C with aqueous solutions containing magnesium nitrate, zinc acetate, erbium acetate, gallium nitrate, and indium nitrate precursors. The effects of Ga [...] Read more.
The p-Si/n-MgZnO:Er/Ga2O3/ZnO:In diodes with different Ga2O3 thicknesses were fabricated through spray pyrolysis deposition at 450 °C with aqueous solutions containing magnesium nitrate, zinc acetate, erbium acetate, gallium nitrate, and indium nitrate precursors. The effects of Ga2O3 layer thickness on the diode properties were investigated. For the deposited films, a combined tiny hexagonal slices and small blocks surface morphology was characterized by scanning electron microscopy for all samples. Diodes were formed after In and Ag deposition on the back side and top side, respectively. The current-voltage characteristics and luminescence spectra are studied. With the increasing of Ga2O3 thickness, the diode forward bias resistance increases while the reverse biased dark current shows the decrease-increase characters. The Er ion corresponded green light emission was characterized for the diode under reverse biased breakdown condition. The increased luminescent intensity with low turn-on current behaviors was characterized by the diode with a Ga2O3 thickness of 4.9 nm. With the diode electrical and luminescence analysis, the effect of the Ga2O3 barrier layer on the diode was discussed. The Ga2O3 barrier layer improves performance for rare earth-related light-emitting devices. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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12 pages, 4404 KiB  
Article
Gain Properties of the Single Cell of a One-Dimensional Photonic Crystal with PT Symmetry
by Piotr Witoński, Agnieszka Mossakowska-Wyszyńska and Paweł Szczepański
Crystals 2023, 13(2), 258; https://doi.org/10.3390/cryst13020258 - 02 Feb 2023
Viewed by 1060
Abstract
In this paper, an analysis of gain properties of a single primitive cell of a one-dimensional photonic crystal with parity–time symmetry is demonstrated for the first time. The proposed simple model makes it possible to study the transmission and amplification properties of the [...] Read more.
In this paper, an analysis of gain properties of a single primitive cell of a one-dimensional photonic crystal with parity–time symmetry is demonstrated for the first time. The proposed simple model makes it possible to study the transmission and amplification properties of the investigated cell made of a wide range of optical materials, taking into account the refractive index of the surrounding medium. This analysis is carried out with the use of a transfer matrix method. The obtained characteristics allow indicating the optimal size of the studied structure providing wave amplification, i.e., a transmittance greater than unity. In this case, the increase in the wave intensity in the gain layer exceeds its decrease in the loss layer. This effect is illustrated with the distributions of the electromagnetic field of waves propagating inside the cell. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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12 pages, 2295 KiB  
Article
Investigation into the Characteristics of Double-Layer Transparent Conductive Oxide ITO/TNO Anti-Reflection Coating for Silicon Solar Cells
by Yih-Shing Lee, Li-Yang Chuang, Cheng-Jia Tang, Zi-Zhu Yan, Bing-Shin Le and Cheng-Chung Jaing
Crystals 2023, 13(1), 80; https://doi.org/10.3390/cryst13010080 - 01 Jan 2023
Viewed by 1417
Abstract
In this study, indium–tin oxide (ITO)/Nb-doping TiO2 (TNO) double-layer transparent conductive oxide (TCO) films deposited using DC magnetron sputtering were used as a surface anti-reflection layer with an overall thickness of 100 nm for double-layer films. The simulated results showed that ITO [...] Read more.
In this study, indium–tin oxide (ITO)/Nb-doping TiO2 (TNO) double-layer transparent conductive oxide (TCO) films deposited using DC magnetron sputtering were used as a surface anti-reflection layer with an overall thickness of 100 nm for double-layer films. The simulated results showed that ITO and TNO thickness combinations of 90 nm/10 nm, 80 nm/20 nm, and 70 nm/30 nm had a higher transmittance and lower reflectance than others in the visible wavelength range. Compared to the single-layer ITO films, for ITO/TNO films deposited on the glass and silicon substrates with an optimum thickness of 80/20 nm, the reflectance was reduced by 5.06% and 4.63%, respectively, at the central wavelength of 550 nm and crystalline silicon photo response wavelength of 900 nm. Moreover, the near-infrared reflectance of the double-layer ITO/TNO with thickness combinations of 90 nm/10 nm, 80 nm/20 nm, and 70 nm/30 nm, when deposited on silicon substrates, was obviously improved by the graded refractive index lamination effect of air (1)/ITO (1.98)/TNO (2.41)/Si (3.9). Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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10 pages, 3289 KiB  
Article
Formation of LiNbO3 Nanocrystals Using the Solvothermal Method
by Gabriella Dravecz, Tamás Kolonits and László Péter
Crystals 2023, 13(1), 77; https://doi.org/10.3390/cryst13010077 - 01 Jan 2023
Cited by 1 | Viewed by 1277
Abstract
The optimization of the parameters of the solvothermal synthesis of lithium niobate (LiNbO3, LN) nanocrystals from Nb2O5 and LiOH was performed. The effects of polyol media, reaction time and Li excess of the starting reagents were investigated. According [...] Read more.
The optimization of the parameters of the solvothermal synthesis of lithium niobate (LiNbO3, LN) nanocrystals from Nb2O5 and LiOH was performed. The effects of polyol media, reaction time and Li excess of the starting reagents were investigated. According to the X-ray diffraction phase analysis, Li3NbO4 and Nb2O5 were also detected besides the LN phase in many samples depending on the ratio of the starting components and the reaction time. The best yield and the most homogeneous LN phase was prepared by using diethylene glycol medium with a Li/Nb ratio of 1.5 and a 72 h reaction time. The size and the shape of the LN particles were characterized by scanning electron microscopy. The particle size distribution was narrow and under 100 nm for all cases. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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10 pages, 3798 KiB  
Article
Electronic, Magnetic and Optical Properties of Double Perovskite Compounds: A First Principle Approach
by Mehtab Ur Rehman, Qun Wang and Yunfei Yu
Crystals 2022, 12(11), 1597; https://doi.org/10.3390/cryst12111597 - 10 Nov 2022
Cited by 3 | Viewed by 4543
Abstract
Double perovskite compounds (DPCs) have gained much more attention due to their versatile character in the fields of electronics and spintronics. Using density functional theory (DFT) we investigated the electronic, magnetic and optical properties of DPC La2BB′O6 where B = [...] Read more.
Double perovskite compounds (DPCs) have gained much more attention due to their versatile character in the fields of electronics and spintronics. Using density functional theory (DFT) we investigated the electronic, magnetic and optical properties of DPC La2BB′O6 where B = Cr, Sc and V and B′ = Co, Ni. The electronic band gaps suggest these compounds are half-metallic (HF) semiconductors in the spin-up channel and metallic in the spin-down channel. Magnetic properties suggest these are ferromagnetic in nature, so all DPCs are half-metallic ferromagnetic (HM-FM). Furthermore, the compound La2CrCoO6 shows outstanding electronic and optical properties, so it can be used in optoelectronic/spintronic devices. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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12 pages, 3476 KiB  
Article
Preparation of Large Volume Solid Argon Crystal and Its Feasibility Test as a Scintillation Material
by Lei Zhang, Chenkai Qiao, Jingjun Zhu, Yu Liu, Yulu Yan, Shin-Ted Lin, Shukui Liu, Changjian Tang and Haoyang Xing
Crystals 2022, 12(10), 1416; https://doi.org/10.3390/cryst12101416 - 07 Oct 2022
Cited by 3 | Viewed by 1859
Abstract
An important background to the liquid argon detectors is that they are caused by the diffusion of radioactive isotopes in a scintillator (liquid phase). This radioactive isotope is produced in argon’s surrounding devices, such as circulation pipelines and liquid argon containers. The solid [...] Read more.
An important background to the liquid argon detectors is that they are caused by the diffusion of radioactive isotopes in a scintillator (liquid phase). This radioactive isotope is produced in argon’s surrounding devices, such as circulation pipelines and liquid argon containers. The solid argon as a scintillation material in the detector can inhibit the diffusion and drift of radioactive isotopes in a solid phase scintillator. Additionally, the structure of a solid argon detector is simple and reduces the total source of radioactive background. In the CDEX-300 detection system, solid argon could substitute for liquid argon as the veto detector, preventing radioactive isotopes drifting to the central main detector (HPGe detectors array) surface to reduce backgrounds. Therefore, solid argon has great potential in the experiments since it is especially helpful to get the lower background in a larger active volume than liquid argon required in those low background detection experiments. This work introduces the preparation process and device of the large volume transparent crystalline argon, the acquisition of scintillation light, and the pulse amplitude spectrum of 137Cs obtained from a prototype detector of transparent solid argon crystal. The results show that the scheme proposed in this study can successfully produce a large volume transparent crystalline argon detector, the scintillation light signals can be effectively obtained from the solid argon scintillator, and the corresponding pulse amplitude spectrum is given. This work indicates that it is feasible to develop a solid argon crystal scintillation detector by using our approach. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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11 pages, 2215 KiB  
Article
Low-Frequency Vibration Sensor with Dual-Fiber Fabry–Perot Interferometer Using a Low-Coherence LED
by Mu-Chun Wang, Shou-Yen Chao, Chun-Yeon Lin, Cheng-Hsun-Tony Chang and Wen-How Lan
Crystals 2022, 12(8), 1079; https://doi.org/10.3390/cryst12081079 - 01 Aug 2022
Cited by 10 | Viewed by 1758
Abstract
In this paper, we propose a dual-fiberoptic Fabry–Perot interferometer (FFPI) sensing system integrated with a low-cost and low-coherence light-emitting diode (LED) as a light source to detect dynamic vibration caused by acoustic waves with a cut-off frequency of 200 Hz. When the acoustic [...] Read more.
In this paper, we propose a dual-fiberoptic Fabry–Perot interferometer (FFPI) sensing system integrated with a low-cost and low-coherence light-emitting diode (LED) as a light source to detect dynamic vibration caused by acoustic waves with a cut-off frequency of 200 Hz. When the acoustic signals are applied, the sensing FFPI on a Styrofoam sheet provides the function of partially transforming the longitudinal energy as the transverse energy generates a phase shift in the sensing FFPI cavity. The light reflected from the sensor is demodulated by the reference FFPI to extract the measurand. The low-power (sub-nW) optical signals are transferred into electrical signals, processed by a designed optical receiver, and recorded for data analysis. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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14 pages, 6025 KiB  
Article
Fabricating High-Conduction and High-Transparency Tungsten-Doped Zinc Oxide Films by Pulse Laser Deposition Technique
by Po-Chuan Pan, Horng-Show Koo, De-Xuan Chen and Chien-Ming Chen
Crystals 2022, 12(8), 1032; https://doi.org/10.3390/cryst12081032 - 25 Jul 2022
Cited by 2 | Viewed by 1397
Abstract
Utilising a pulse laser deposition technique, 1.0 wt.% tungsten-doped zinc oxide (WZO) films were fabricated under different growth temperatures (200–400 °C), and their structural, optical, morphological, and electrical properties were discussed. The crystalline structures of the WZO target and films were examined by [...] Read more.
Utilising a pulse laser deposition technique, 1.0 wt.% tungsten-doped zinc oxide (WZO) films were fabricated under different growth temperatures (200–400 °C), and their structural, optical, morphological, and electrical properties were discussed. The crystalline structures of the WZO target and films were examined by X-ray diffraction (XRD) analysis, and preferred orientations along the strong c-axis (002) were strongly observed for all growth temperatures. All WZO films demonstrated transparencies above 75%, along with a wide spectral range (400–700 nm). Their bandgap values ranged between 3.21 and 3.35 eV and their optimised resistivity, which was significantly influenced by the growth temperature, was measured as 1.97 × 10−3 Ω cm. Further, the electrical characteristics of the WZO films were investigated under different W-doping amounts (1.0–9.0 wt.%) and a constant growth temperature (300 °C), and the results indicated that the carrier mobility showed an opposite tendency to the W-doping percentage. In addition, the elemental compositions of the WZO films and pristine ZnO films were comparatively studied in terms of Zn, O, and W contents, via X-ray photoelectron spectroscopy (XPS) analysis. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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14 pages, 5863 KiB  
Article
Ion-Track Template Synthesis and Characterization of ZnSeO3 Nanocrystals
by Alma Dauletbekova, Aiman Akylbekova, Gulnaz Sarsekhan, Abay Usseinov, Zein Baimukhanov, Artem Kozlovskiy, Liudmila A. Vlasukova, Fadey F. Komarov, Anatoli I. Popov and Abdirash T. Akilbekov
Crystals 2022, 12(6), 817; https://doi.org/10.3390/cryst12060817 - 09 Jun 2022
Cited by 11 | Viewed by 1947
Abstract
ZnSeO3 nanocrystals with an orthorhombic structure were synthesized by electrochemical and chemical deposition into SiO2/Si ion-track template formed by 200 MeV Xe ion irradiation with the fluence of 107 ions/cm2. The lattice parameters determined by the X-ray [...] Read more.
ZnSeO3 nanocrystals with an orthorhombic structure were synthesized by electrochemical and chemical deposition into SiO2/Si ion-track template formed by 200 MeV Xe ion irradiation with the fluence of 107 ions/cm2. The lattice parameters determined by the X-ray diffraction and calculated by the CRYSTAL computer program package are very close to each other. It was found that ZnSeO3 has a direct band gap of 3.8 eV at the Γ-point. The photoluminescence excited by photons at 300 nm has a low intensity, arising mainly due to zinc and oxygen vacancies. Photoluminescence excited by photons with a wavelength of 300 nm has a very low intensity, presumably due to electronic transitions of zinc and oxygen vacancies. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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11 pages, 1845 KiB  
Article
Improved Optoelectronic Characteristics of Ga-In co-Doped ZnO UV Photodetectors by Asymmetric Metal Contact Structure
by Chien-Yie Tsay, Hsuan-Meng Tsai and Yun-Chi Chen
Crystals 2022, 12(5), 746; https://doi.org/10.3390/cryst12050746 - 23 May 2022
Cited by 6 | Viewed by 1681
Abstract
Transparent Ga and In co-doped ZnO (ZnO:Ga-In) semiconductor thin films were deposited on Corning glass substrates by the sol-gel spin-coating process. The ZnO:Ga-In thin films were used as the sensing layer of metal–semiconductor–metal (MSM)-type ultraviolet (UV) photodetectors (PDs). In this study, the optoelectronic [...] Read more.
Transparent Ga and In co-doped ZnO (ZnO:Ga-In) semiconductor thin films were deposited on Corning glass substrates by the sol-gel spin-coating process. The ZnO:Ga-In thin films were used as the sensing layer of metal–semiconductor–metal (MSM)-type ultraviolet (UV) photodetectors (PDs). In this study, the optoelectronic characteristics of ZnO:Ga-In MSM PDs with symmetrical interdigital electrodes (Al–Al) and asymmetrical interdigital electrodes (Al–Au) were compared. The as-prepared ZnO:Ga-In thin films were polycrystalline, and they had a single-phase hexagonal wurtzite structure and high transparency (~88.4%) in the visible region. The MSM-PDs with asymmetric electrodes had significantly reduced dark current (9.6 × 10−5 A at 5 V) according to the current-voltage (I-V) characteristics and higher photoresponse properties than those of the MSM-PDs with symmetric electrodes, according to the current-time (I-t) characteristics. In addition, the Al–Au devices were self-powered without an applied bias voltage. The photocurrent was 6.0 × 10−5 A; the sensitivity and responsivity were 0.25 and 0.03 mA/W, respectively, under UV illumination. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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14 pages, 3023 KiB  
Article
Band Gap and Topology of 1D Perovskite-Derived Hybrid Lead Halide Structures
by Ekaterina I. Marchenko, Sergey A. Fateev, Eugene A. Goodilin and Alexey B. Tarasov
Crystals 2022, 12(5), 657; https://doi.org/10.3390/cryst12050657 - 04 May 2022
Cited by 2 | Viewed by 2124
Abstract
The unprecedented structural flexibility of hybrid halide perovskites is accompanied by a wide range of useful optoelectronic properties, causing a high interest in this family of materials. However, there are no systematic studies yet on the relationships between the topology of structures derived [...] Read more.
The unprecedented structural flexibility of hybrid halide perovskites is accompanied by a wide range of useful optoelectronic properties, causing a high interest in this family of materials. However, there are no systematic studies yet on the relationships between the topology of structures derived of chain 1D hybrid halide perovskites and their optoelectronic properties such as the band gap as already reported for 3D and 2D hybrid halide perovskites. In the present work, we introduce a rational classification of hybrid lead iodide 1D structures. We provide a theoretical assessment of the relationship between the topology of 1D hybrid halide perovskite-derived structures with vertex-connected octahedra and show that the distortions of geometry of the chains of PbI6 octahedra are the main parameters affecting the band gap value while the distance between the chains of vertex-connected octahedra has a minor effect on the band gap. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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13 pages, 4397 KiB  
Article
Radiation Modification of Optical Characteristics of LiNbO3:Zn and LiNbO3:Mg Crystals
by Mikhail Palatnikov, Nikolay Sidorov, Sergey Panasjuk, Natalya Teplyakova and Olga Makarova
Crystals 2022, 12(5), 600; https://doi.org/10.3390/cryst12050600 - 25 Apr 2022
Cited by 2 | Viewed by 1851
Abstract
The modification of the optical characteristics of LiNbO3:Zn and LiNbO3:Mg crystals grown by the Czochralski method was investigated using β and γ radiation. The photorefractive effect was found to be inhibited by ionizing radiation in the LiNbO3:Zn [...] Read more.
The modification of the optical characteristics of LiNbO3:Zn and LiNbO3:Mg crystals grown by the Czochralski method was investigated using β and γ radiation. The photorefractive effect was found to be inhibited by ionizing radiation in the LiNbO3:Zn ([ZnO] ≈ 2.1 mol%) crystal, which belonged to a below-threshold concentration range. The inhibition was attributed to a stepwise radiation annealing of charged defects. Ionizing radiation increased the general optical uniformity of above-threshold crystals LiNbO3:Zn ([ZnO] ≈ 5.9 mol%) and LiNbO3:Mg([MgO] ≈ 5.6 mol%). In addition, we determined that radiation annealing substantially influenced photorefraction dynamics in lightly doped LiNbO3:Zn ([ZnO] ≈ 0.1 mol%) crystals, which widens their application areas. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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8 pages, 3558 KiB  
Article
Synthesis of AlN Nanowires by Al-Sn Flux Method
by Haoxin Mu, Jianli Chen, Lujie Li, Yonggui Yu, Wencheng Ma, Xiaofang Qi, Zhanggui Hu and Yongkuan Xu
Crystals 2022, 12(4), 516; https://doi.org/10.3390/cryst12040516 - 08 Apr 2022
Viewed by 1403
Abstract
This paper presents a recent study on the synthesis of AlN nanowires. AlN nanowires were successfully prepared on sapphire substrate by the Al-Sn flux method. The obtained nanowires were hundreds of nanometers in diameter and tens of microns in length. The results of [...] Read more.
This paper presents a recent study on the synthesis of AlN nanowires. AlN nanowires were successfully prepared on sapphire substrate by the Al-Sn flux method. The obtained nanowires were hundreds of nanometers in diameter and tens of microns in length. The results of transmission electron microscopy (TEM) show that the growth direction of AlN nanowires was perpendicular to the C axis. The photoluminescence (PL) spectrum of AlN nanowires shows a broad peak, which is ascribed to the defect levels in the AlN bandgap. This work provides a novel method for growing AlN nanowires, which offers a potential material for the application of photoelectron devices. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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10 pages, 2661 KiB  
Article
Scintillation Properties of Pr-Doped Lanthanum Pyrosilicate Single Crystals
by Prom Kantuptim, Takumi Kato, Daisuke Nakauchi, Noriaki Kawaguchi and Takayuki Yanagida
Crystals 2022, 12(4), 459; https://doi.org/10.3390/cryst12040459 - 25 Mar 2022
Cited by 6 | Viewed by 2426
Abstract
Five samples of lanthanum pyrosilicate (La2Si2O7) single crystals with 0.5–10.0% Praseodymium (Pr)-doping concentrations were synthesized by the floating-zone method. Photoluminescence and scintillation properties of these crystals were investigated in this study for the first time. The multiple [...] Read more.
Five samples of lanthanum pyrosilicate (La2Si2O7) single crystals with 0.5–10.0% Praseodymium (Pr)-doping concentrations were synthesized by the floating-zone method. Photoluminescence and scintillation properties of these crystals were investigated in this study for the first time. The multiple emissions from electron transitions of Pr3+ were observed on both a photoluminescence emission map and scintillation spectra, including the desired emission band of Pr3+ 5d–4f transition at 250–310 nm. The major photoluminescence and scintillation decay times were approximately 19 and 26 ns, respectively. When compared with commercial scintillators such as Tl-doped cesium iodide (CsI), the Pr-doped La2Si2O7 samples presented a respectively low afterglow level of 32 ppm after 20 ms of X-ray irradiation. Under 662 keV γ-ray irradiation from 137Cs, the 3.0% Pr-doped La2Si2O7 sample presented a scintillation light yield of 3200 ph/MeV, which was the best value among the tested samples. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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11 pages, 4936 KiB  
Article
Carrier Injection to In0.4Ga0.6As/GaAs Surface Quantum Dots in Coupled Hybrid Nanostructures
by Jingtao Liu, Shiping Luo, Xiaohui Liu, Ying Wang, Chunsheng Wang, Shufang Wang, Guangsheng Fu, Yuriy I. Mazur, Morgan E. Ware, Gregory J. Salamo and Baolai Liang
Crystals 2022, 12(3), 319; https://doi.org/10.3390/cryst12030319 - 24 Feb 2022
Cited by 3 | Viewed by 1522
Abstract
Stacking growth of the InGaAs quantum dots (QDs) on top of a carrier injection layer is a very useful strategy to develop QD devices. This research aims to study the carrier injection effect in hybrid structures with a layer of In0.4Ga [...] Read more.
Stacking growth of the InGaAs quantum dots (QDs) on top of a carrier injection layer is a very useful strategy to develop QD devices. This research aims to study the carrier injection effect in hybrid structures with a layer of In0.4Ga0.6As surface quantum dots (SQDs), coupled to an injection layer of either one layer of In0.4Ga0.6As buried QDs (BQDs) or an In0.15Ga0.85As quantum well (QW), both through a 10 nm GaAs thin spacer. Spectroscopic measurements show that carrier capture and emission efficiency for SQDs in the BQD injection structure is better than that of the QW injection, due to strong physical and electrical coupling between the two QD layers. In the case of QW injection, although most carriers can be collected into the QW, they then tunnel into the wetting layer of the SQDs and are subsequently lost to surface states via non-radiative recombination. Therefore, the QW as an injection source for SQDs may not work as well as the BQDs for stacking coupled SQDs structures. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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8 pages, 3336 KiB  
Article
Using Powder Diffraction Patterns to Calibrate the Module Geometry of a Pixel Detector
by Jonathan P. Wright, Carlotta Giacobbe and Eleanor Lawrence Bright
Crystals 2022, 12(2), 255; https://doi.org/10.3390/cryst12020255 - 14 Feb 2022
Cited by 5 | Viewed by 2929
Abstract
The precision and accuracy of diffraction measurements with 2D area detectors depends on how well the experimental geometry is known. A method is described to measure the module geometry in order to obtain accurate strain data using a new Eiger2 4M CdTe detector. [...] Read more.
The precision and accuracy of diffraction measurements with 2D area detectors depends on how well the experimental geometry is known. A method is described to measure the module geometry in order to obtain accurate strain data using a new Eiger2 4M CdTe detector. Smooth Debye–Scherrer powder diffraction rings with excellent signal to noise were collected by using a fine-grained sample of CeO2. From these powder patterns, the different components of the module alignment errors could be observed when the overall detector position was moved. A least squares fitting method was used to refine the detector module and scattering geometry for a series of powder patterns with different beam centers. A precision that is around 1/350 pixel for the module positions was obtained from the fit. This calibration was checked by free refinement of the unit cell of a silicon crystal that gave a maximum residual strain value of 2.1 × 10−5 as the deviation from cubic symmetry. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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8 pages, 2713 KiB  
Opinion
The Impact of Hysteresis Effect on Device Characteristic and Reliability for Various Fin-Widths Tri-Gate Hf0.5Zr0.5O2 Ferroelectric FinFET
by Wen-Qi Zhang, Po-Tang Wu, Yu-Heng Lin and Yi-Lin Yang
Crystals 2023, 13(4), 628; https://doi.org/10.3390/cryst13040628 - 06 Apr 2023
Viewed by 1355
Abstract
In this study, we developed a facilitated ferroelectric high-k/metal-gate n-type FinFET based on Hf0.5Zr0.5O2. We investigated the impact of the hysteresis effect on device characteristics of various fin-widths and the degradation induced by stress on the ferroelectric [...] Read more.
In this study, we developed a facilitated ferroelectric high-k/metal-gate n-type FinFET based on Hf0.5Zr0.5O2. We investigated the impact of the hysteresis effect on device characteristics of various fin-widths and the degradation induced by stress on the ferroelectric FinFET (Fe-FinFET). We clarified the electrical characteristics of the device and conducted related reliability inspections. For the Fe-FinFET, the hysteresis behavior of the Hf0.5Zr0.5O2-based gate stack in the Si-fin body is apparent, especially at narrower fin-widths, which affects device performance and reliability under voltage stress. The gate ferroelectric film is worsened after voltage stress with higher impact ionization, resulting in hysteresis degradation and serious induced device performance degradation. It is suggested that the hysteresis degradation is caused by both a shift in polarization of the gate ferroelectric film and generation of interface traps after high-energy carrier stress, which was confirmed by crystal structure inspection. Full article
(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)
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