Wide Bandgap Semiconductor Photonic Devices

A special issue of Photonics (ISSN 2304-6732). This special issue belongs to the section "Optoelectronics and Optical Materials".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 45032

Special Issue Editors

Rochester Institute of Technology, New York, NY, USA
Interests: wide bandgap semiconductors; ultraviolet photonic devices; semiconductor light-emitting diodes and lasers; nanowire photonic devices

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Guest Editor
Department of Materials Design and Innovation, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260, USA
Interests: wide bandgap semiconductors; synthesis; processing and devices
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A0E9, Canada
Interests: semiconductor materials; nanowires, molecular beam epitaxy; optoelectronic devices; light-emitting diodes; lasers; artificial photosynthesis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The pursuit of wide bandgap semiconductor photonic devices has led to a series of fundamental breakthroughs, especially the Nobel prize winning blue light-emitting diodes (LEDs) based on group III-Nitride materials. For shorter wavelengths, wide bandgap semiconductor ultraviolet (UV) photonic devices have been explored for both photon emission and detection. For the past decades, developments have been carried out for wide bandgap semiconductor photonic devices on novel materials, device physics, active region design, and device fabrication/packaging.

 This Special Issue focuses on the most recent advances in the field of wide bandgap semiconductor photonic devices such as LEDs, lasers or photodetectors. Topics will include, but are not limited to development of advanced device physics; research of novel wide bandgap materials including 2D materials; exploration of nanostructured active regions such as nanowires or quantum dots; as well as study of non-classical device concepts. New methods of fabricating semiconductor photonic devices to achieve higher output power and quantum efficiency are also welcome.

Dr. Jing Zhang
Guest Editor

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Published Papers (10 papers)

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Research

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13 pages, 2186 KiB  
Article
Near Unity PLQY and High Stability of Barium Thiocyanate Based All-Inorganic Perovskites and Their Applications in White Light-Emitting Diodes
by Gopi Chandra Adhikari, Saroj Thapa, Yang Yue, Hongyang Zhu and Peifen Zhu
Photonics 2021, 8(6), 209; https://doi.org/10.3390/photonics8060209 - 9 Jun 2021
Cited by 10 | Viewed by 4277
Abstract
All-inorganic lead halide perovskite (CsPbX3) nanocrystals (NCs) have emerged as a highly promising new generation of light emitters due to their extraordinary photophysical properties. However, the performance of these semiconducting NCs is undermined due to the inherent toxicity of lead and [...] Read more.
All-inorganic lead halide perovskite (CsPbX3) nanocrystals (NCs) have emerged as a highly promising new generation of light emitters due to their extraordinary photophysical properties. However, the performance of these semiconducting NCs is undermined due to the inherent toxicity of lead and long-term environmental stability. Here, we report the addition of B-site cation and X-site anion (pseudo-halide) concurrently using Ba(SCN)2 (≤50%) in CsPbX3 NCs to reduce the lead and improve the photophysical properties and stability. The as-grown particles demonstrated an analogous structure with an almost identical lattice constant and a fluctuation of particle size without altering the morphology of particles. Photoluminescence quantum yield is enhanced up to near unity (~98%) by taking advantage of concomitant doping at the B- and X-site of the structure. Benefitted from the defect reductions and stronger bonding interaction between Pb2+ and SCN ions, Ba(SCN)2-based NCs exhibit improved stability towards air and moisture compared to the host NCs. The doped NCs retain higher PLQY (as high as seven times) compared to the host NCs) when stored in an ambient atmosphere for more than 176 days. A novel 3D-printed multiplex color conversion layer was used to fabricate a white light-emitting diode (LED). The obtained white light shows a correlated color temperature of 6764 K, a color rendering index of 87, and luminous efficacy of radiation of 333 lm/W. In summary, this work proposes a facile route to treat sensitive lead halide perovskite NCs and to fabricate LEDs by using a low-cost large-scale 3-D printing method, which would serve as a foundation for fabricating high-quality optoelectronic devices for near future lighting technologies. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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11 pages, 3142 KiB  
Article
Efficient Carrier Recombination in InGaN Pyramidal µ-LEDs Obtained through Selective Area Growth
by Jie’an Jiang, Houqiang Xu, Li Chen, Long Yan, Jason Hoo, Shiping Guo, Yuheng Zeng, Wei Guo and Jichun Ye
Photonics 2021, 8(5), 157; https://doi.org/10.3390/photonics8050157 - 10 May 2021
Cited by 1 | Viewed by 3072
Abstract
Pyramid-shaped InGaN/GaN micro-light-emitting diodes (μ-LEDs) were grown on a sapphire substrate using the selective area growth technique. A stable emission wavelength of a single μ-LED pyramid at 412 nm was observed under an injection current from 0.05 to 20 mA, [...] Read more.
Pyramid-shaped InGaN/GaN micro-light-emitting diodes (μ-LEDs) were grown on a sapphire substrate using the selective area growth technique. A stable emission wavelength of a single μ-LED pyramid at 412 nm was observed under an injection current from 0.05 to 20 mA, despite the non-uniformity of the thickness and composition of the multiple quantum wells (MQWs) on the sidewall. An efficient carrier confinement and, thus, a high luminescence intensity were demonstrated in the middle of the sidewall through spatial-resolved cathodoluminescence (CL) characterization and were predicted by theoretical simulations. An ultra-high output power density of 1.37 kW/cm2 was obtained from the single μ-LED pyramid, illustrating its great potential for application in high-brightness micro-displays and in virtual reality and augmented reality (VR and AR) applications. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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9 pages, 2735 KiB  
Communication
Size-Dependent Quantum Efficiency of Flip-Chip Light-Emitting Diodes at High Current Injection Conditions
by Xingfei Zhang, Yan Li, Zhicong Li, Zhenlin Miao, Meng Liang, Yiyun Zhang, Xiaoyan Yi, Guohong Wang and Jinmin Li
Photonics 2021, 8(4), 88; https://doi.org/10.3390/photonics8040088 - 24 Mar 2021
Cited by 4 | Viewed by 2526
Abstract
Versatile applications call for InGaN-based light-emitting diodes (LEDs) to operate at ultra-high current densities with high quantum efficiency. In this work, we investigated the size-dependent effects of the electrical and optical performance of LEDs as increasing the current density up to 100 A/cm [...] Read more.
Versatile applications call for InGaN-based light-emitting diodes (LEDs) to operate at ultra-high current densities with high quantum efficiency. In this work, we investigated the size-dependent effects of the electrical and optical performance of LEDs as increasing the current density up to 100 A/cm2, which demonstrated that mini-strip flip-chip LEDs were superior option to achieve better performance. In detail, at a current density of 100 A/cm2, the light output power density of these mini-strip LEDs was improved by about 6.1 W/cm2, leading to an improvement in the wall-plug efficiency by 4.23%, while the operating temperature was reduced by 11.3 °C, as compared with the large-sized LEDs. This could be attributed to the increase in the sidewall light extraction, alleviated current crowding effect, and improved heat dissipation. This work suggests an array of mini-strip LEDs would provide an option in achieving higher luminescent efficiency at ultrahigh current injection conditions for various applications. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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7 pages, 2169 KiB  
Communication
Development of Micron Sized Photonic Devices Based on Deep GaN Etching
by Karim Dogheche, Bandar Alshehri, Galles Patriache and Elhadj Dogheche
Photonics 2021, 8(3), 68; https://doi.org/10.3390/photonics8030068 - 2 Mar 2021
Cited by 4 | Viewed by 3106
Abstract
In order to design and development efficient III-nitride based optoelectronic devices, technological processes require a major effort. We propose here a detailed review focussing on the etching procedure as a key step for enabling high date rate performances. In our reported research activity, [...] Read more.
In order to design and development efficient III-nitride based optoelectronic devices, technological processes require a major effort. We propose here a detailed review focussing on the etching procedure as a key step for enabling high date rate performances. In our reported research activity, dry etching of an InGaN/GaN heterogeneous structure was investigated by using an inductively coupled plasma reactive ion etching (ICP-RIE). We considered different combinations of etch mask (Ni, SiO2, resist), focussing on the optimization of the deep etching process. A GaN mesa process with an etching depth up to 6 µm was performed in Cl2/Ar-based plasmas using ICP reactors for LEDs dimen sions ranging from 5 to 150 µm². Our strategy was directed toward the mesa formation for vertical-type diode applications, where etch depths are relatively large. Etch characteristics were studied as a function of ICP parameters (RF power, chamber pressure, fixed total flow rate). Surface morphology, etch rates and sidewall profiles observed into InGaN/GaN structures were compared under different types of etching masks. For deep etching up to few microns into the GaN template, we state that a Ni or SiO2 mask is more suitable to obtain a good selectivity and vertical etch profiles. The optimized etch rate was about 200nm/min under moderate ICP conditions. We applied these conditions for the fabrication of micro/nano LEDs dedicated to LiFi applications. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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10 pages, 3759 KiB  
Article
The Optical Properties of InGaN/GaN Nanorods Fabricated on (-201) β-Ga2O3 Substrate for Vertical Light Emitting Diodes
by Jie Zhao, Weijiang Li, Lulu Wang, Xuecheng Wei, Junxi Wang and Tongbo Wei
Photonics 2021, 8(2), 42; https://doi.org/10.3390/photonics8020042 - 6 Feb 2021
Cited by 3 | Viewed by 2979
Abstract
We fabricated InGaN/GaN nanorod light emitting diode (LED) on (-201) β-Ga2O3 substrate via the SiO2 nanosphere lithography and dry-etching techniques. The InGaN/GaN nanorod LED grown on β-Ga2O3 can effectively suppress quantum confined Stark effect (QCSE) compared [...] Read more.
We fabricated InGaN/GaN nanorod light emitting diode (LED) on (-201) β-Ga2O3 substrate via the SiO2 nanosphere lithography and dry-etching techniques. The InGaN/GaN nanorod LED grown on β-Ga2O3 can effectively suppress quantum confined Stark effect (QCSE) compared to planar LED on account of the strain relaxation. With the enhancement of excitation power density, the photoluminescence (PL) peak shows a large blue-shift for the planar LED, while for the nanorod LED, the peak position shift is small. Furthermore, the simulations also show that the light extraction efficiency (LEE) of the nanorod LED is approximately seven times as high as that of the planar LED. Obviously, the InGaN/GaN/β-Ga2O3 nanorod LED is conducive to improving the optical performance relative to planar LED, and the present work may lay the groundwork for future development of the GaN-based vertical light emitting diodes (VLEDs) on β-Ga2O3 substrate. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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6 pages, 3875 KiB  
Communication
Effect of Si Doping on the Performance of GaN Schottky Barrier Ultraviolet Photodetector Grown on Si Substrate
by Fangzhou Liang, Wen Chen, Meixin Feng, Yingnan Huang, Jianxun Liu, Xiujian Sun, Xiaoning Zhan, Qian Sun, Qibao Wu and Hui Yang
Photonics 2021, 8(2), 28; https://doi.org/10.3390/photonics8020028 - 23 Jan 2021
Cited by 8 | Viewed by 2896
Abstract
GaN Schottky barrier ultraviolet photodetectors with unintentionally doped GaN and lightly Si-doped n-GaN absorption layers were successfully fabricated, respectively. The high-quality GaN films on the Si substrate both have a fairly low dislocation density and point defect concentration. More importantly, the [...] Read more.
GaN Schottky barrier ultraviolet photodetectors with unintentionally doped GaN and lightly Si-doped n-GaN absorption layers were successfully fabricated, respectively. The high-quality GaN films on the Si substrate both have a fairly low dislocation density and point defect concentration. More importantly, the effect of Si doping on the performance of the GaN-on-Si Schottky barrier ultraviolet photodetector was studied. It was found that light Si doping in the absorption layer can significantly increase the responsivity under reverse bias, which might be attributed to the persistent photoconductivity that originates from the lowering of the Schottky barrier height. In addition, the devices with unintentionally doped GaN demonstrated a relatively high-speed photo response. We briefly studied the mechanism of changes in Schottky barrier, dark current and the characteristic of response time. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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13 pages, 2278 KiB  
Article
AlGaN-Delta-GaN Quantum Well for DUV LEDs
by Cheng Liu, Bryan Melanson and Jing Zhang
Photonics 2020, 7(4), 87; https://doi.org/10.3390/photonics7040087 - 3 Oct 2020
Cited by 14 | Viewed by 2849
Abstract
AlGaN-delta-GaN quantum well (QW) structures have been demonstrated to be good candidates for the realization of high-efficiency deep-ultraviolet (DUV) light-emitting diodes (LEDs). However, such heterostructures are still not fully understood. This study focuses on investigation of the optical properties and efficiency of the [...] Read more.
AlGaN-delta-GaN quantum well (QW) structures have been demonstrated to be good candidates for the realization of high-efficiency deep-ultraviolet (DUV) light-emitting diodes (LEDs). However, such heterostructures are still not fully understood. This study focuses on investigation of the optical properties and efficiency of the AlGaN-delta-GaN QW structures using self-consistent six-band k⸱p modelling and finite difference time domain (FDTD) simulations. Structures with different Al contents in the AlxGa1−xN sub-QW and AlyGa1−yN barrier regions are examined in detail. Results show that the emission wavelength (λ) can be engineered through manipulation of delta-GaN layer thickness, sub-QW Al content (x), and barrier Al content (y), while maintaining a large spontaneous emission rate corresponding to around 90% radiative recombination efficiency (ηRAD). In addition, due to the dominant transverse-electric (TE)-polarized emission from the AlGaN-delta-GaN QW structure, the light extraction efficiency (ηEXT) is greatly enhanced when compared to a conventional AlGaN QW. Combined with the large ηRAD, this leads to the significant enhancement of external quantum efficiency (ηEQE), indicating that AlGaN-delta-GaN structures could be a promising solution for high-efficiency DUV LEDs. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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13 pages, 2806 KiB  
Article
Insights of Hysteresis Behaviors in Perovskite Solar Cells from a Mixed Drift-Diffusion Model Coupled with Recombination
by Chongqiu Yang, Xiaobiao Shan and Tao Xie
Photonics 2020, 7(3), 47; https://doi.org/10.3390/photonics7030047 - 3 Jul 2020
Cited by 11 | Viewed by 4701
Abstract
Hysteresis in perovskite solar cells is a notorious issue limiting its development in stability, reproducibility and efficiency. Ions’ migration coupled with charges’ recombination are indispensable factors to generate the hysteretic curves on the basis of experimental and theoretical calculation studies, however, the underlying [...] Read more.
Hysteresis in perovskite solar cells is a notorious issue limiting its development in stability, reproducibility and efficiency. Ions’ migration coupled with charges’ recombination are indispensable factors to generate the hysteretic curves on the basis of experimental and theoretical calculation studies, however, the underlying physical characteristics are rarely clarified. Here, a mixed electronic-ionic drift-diffusion model combined with bulk and interfacial recombination is investigated. Positive and negative ion species could drift to and accumulate at interfaces between the perovskite/transport layers, influencing internal electric potential profiles and delaying the charges’ ejection to the transport layers. The charges might recombine spontaneously or trap-assisted, reducing the total amount of electrons and holes collected in the external circuit, leading to a diminished photocurrent. Moreover, our calculations indicate that an appropriate measurement protocol is really essential to evaluate the device performance precisely and to suppress J–V hysteresis. Meanwhile, a negligible hysteretic loop could be obtained by balancing the material properties of the transport layers and restraining the ions mobility in the perovskite layer. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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Review

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25 pages, 5580 KiB  
Review
Recent Progress of Electrically Pumped AlGaN Diode Lasers in the UV-B and -C Bands
by Syed M. N. Hasan, Weicheng You, Md Saiful Islam Sumon and Shamsul Arafin
Photonics 2021, 8(7), 267; https://doi.org/10.3390/photonics8070267 - 8 Jul 2021
Cited by 16 | Viewed by 5867
Abstract
The development of electrically pumped semiconductor diode lasers emitting at the ultraviolet (UV)-B and -C spectral bands has been an active area of research over the past several years, motivated by a wide range of emerging applications. III-Nitride materials and their alloys, in [...] Read more.
The development of electrically pumped semiconductor diode lasers emitting at the ultraviolet (UV)-B and -C spectral bands has been an active area of research over the past several years, motivated by a wide range of emerging applications. III-Nitride materials and their alloys, in particular AlGaN, are the material of choice for the development of this ultrashort-wavelength laser technology. Despite significant progress in AlGaN-based light-emitting diodes (LEDs), the technological advancement and innovation in diode lasers at these spectral bands is lagging due to several technical challenges. Here, the authors review the progress of AlGaN electrically-pumped lasers with respect to very recent achievements made by the scientific community. The devices based on both thin films and nanowires demonstrated to date will be discussed in this review. The state-of-the-art growth technologies, such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD); and various foreign substrates/templates used for the laser demonstrations will be highlighted. We will also outline technical challenges associated with the laser development, which must be overcome in order to achieve a critical technological breakthrough and fully realize the potential of these lasers. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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19 pages, 3961 KiB  
Review
Perspectives on UVC LED: Its Progress and Application
by Tsung-Chi Hsu, Yu-Tsai Teng, Yen-Wei Yeh, Xiaotong Fan, Kuo-Hsiung Chu, Su-Hui Lin, Kuo-Kuang Yeh, Po-Tsung Lee, Yue Lin, Zhong Chen, Tingzhu Wu and Hao-Chung Kuo
Photonics 2021, 8(6), 196; https://doi.org/10.3390/photonics8060196 - 31 May 2021
Cited by 63 | Viewed by 11420
Abstract
High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the [...] Read more.
High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductor Photonic Devices)
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