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Micromachines
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Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III
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Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D1: Semiconductor Devices".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 34728

Special Issue Editors

Prof. Dr. Alessandro Chini

E-Mail Website
Guest Editor
Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, via P. Vivarelli 10, 41125 Modena, Italy
Interests: RF and power GaN HEMTs design and characterization; III-V devices reliability; numerical simulations
Dr. Nicolò Zagni

E-Mail Website
Guest Editor
Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, via P. Vivarelli 10, 41125 Modena, Italy
Interests: semiconductor devices; GaN HEMTs; ferroelectric FETs; reliability

Special Issue Information

Dear Colleagues,

Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer a greater potential reliability in tougher operating conditions. Furthermore, in this framework, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than previously established wide-bandgap semiconductors, such as GaN and SiC, have been created and are thus referred to as “ultra-wide-bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher operation temperatures, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics.

After the success of the first edition edited by Dr. Farid Medjdoub and the second edition edited by Prof. Dr. Giovanni Verzellesi, a third volume of the Special Issue “Wide Bandgap Based Devices: Design, Fabrication, and Applications” is being launched, aiming to collect high-quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. In particular, the following topics are addressed:

  • GaN- and SiC-based devices for power and optoelectronic applications;
  • Ga2O3 substrate development and Ga2O3 thin film growth, doping, and devices;
  • AlN-based emerging material and devices;
  • BN epitaxial growth, characterization, and devices.

Prof. Dr. Alessandro Chini
Dr. Nicolò Zagni
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. Micromachines 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

  • wide bandgap devices (WBG)
  • ultra-wide bandgap devices (UWBG)
  • power
  • optoelectronic
  • GaN
  • Ga2O3
  • AlN
  • SiC
  • BN

Related Special Issues

Published Papers (15 papers)

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Research

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7 pages, 2393 KiB  
Article
Low Trapping Effects and High Electron Confinement in Short AlN/GaN-On-SiC HEMTs by Means of a Thin AlGaN Back Barrier
by Kathia Harrouche, Srisaran Venkatachalam, Lyes Ben-Hammou, François Grandpierron, Etienne Okada and Farid Medjdoub
Micromachines 2023, 14(2), 291; https://doi.org/10.3390/mi14020291 - 22 Jan 2023
Cited by 5 | Viewed by 2311
Abstract
In this paper, we report on an enhancement of mm-wave power performances with a vertically scaled AlN/GaN heterostructure. An AlGaN back barrier is introduced underneath a non-intentionally doped GaN channel layer, enabling the prevention of punch-through effects and related drain leakage current under [...] Read more.
In this paper, we report on an enhancement of mm-wave power performances with a vertically scaled AlN/GaN heterostructure. An AlGaN back barrier is introduced underneath a non-intentionally doped GaN channel layer, enabling the prevention of punch-through effects and related drain leakage current under a high electric field while using a moderate carbon concentration into the buffer. By carefully tuning the Al concentration into the back barrier layer, the optimized heterostructure offers a unique combination of electron confinement and low trapping effects up to high drain bias for a gate length as short as 100 nm. Consequently, pulsed (CW) Load-Pull measurements at 40 GHz revealed outstanding performances with a record power-added efficiency of 70% (66%) under high output power density at VDS = 20 V. These results demonstrate the interest of this approach for future millimeter-wave applications. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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7 pages, 1542 KiB  
Communication
Influence of O2 Flow Rate on the Properties of Ga2O3 Growth by RF Magnetron Sputtering
by Dengyue Li, Hehui Sun, Tong Liu, Hongyan Jin, Zhenghao Li, Yaxin Liu, Donghao Liu and Dongbo Wang
Micromachines 2023, 14(2), 260; https://doi.org/10.3390/mi14020260 - 19 Jan 2023
Cited by 3 | Viewed by 1698
Abstract
The influence of the O2 flow rate on the properties of gallium oxide (Ga2O3) by RF magnetron sputtering was studied. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmittance spectra, and photoluminescence (PL) spectra have [...] Read more.
The influence of the O2 flow rate on the properties of gallium oxide (Ga2O3) by RF magnetron sputtering was studied. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmittance spectra, and photoluminescence (PL) spectra have been employed to study the Ga2O3 thin films. With the increase in oxygen flow rate, both the crystal quality and luminescence intensity of the Ga2O3 samples first decrease and then enhance. All these observations suggested that the reduction in the oxygen defect density is responsible for the improvement in the crystal quality and emission intensity of the material. Our results demonstrated that high-quality Ga2O3 materials could be obtained by adjusting the oxygen flow rate. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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17 pages, 25970 KiB  
Article
Design and Implementation of a SiC-Based Multifunctional Back-to-Back Three-Phase Inverter for Advanced Microgrid Operation
by Chao-Tsung Ma and Zhi-Yuan Zheng
Micromachines 2023, 14(1), 134; https://doi.org/10.3390/mi14010134 - 03 Jan 2023
Viewed by 1212
Abstract
Because of the worldwide trend of microgrid (MG) and renewable energy (RE)-based distributed power generation (DG), advanced power flow control schemes with wide bandgap (WBG) semiconductor technologies to ensure high-level performance of grid-connected MGs is one of the crucial research topics. In grid-connected [...] Read more.
Because of the worldwide trend of microgrid (MG) and renewable energy (RE)-based distributed power generation (DG), advanced power flow control schemes with wide bandgap (WBG) semiconductor technologies to ensure high-level performance of grid-connected MGs is one of the crucial research topics. In grid-connected MGs, a static switch (SS) is commonly used at the point of common coupling (PCC) of two systems. In this paper, the role of SS is replaced by a SiC-based three-phase back-to-back (BTB) inverter system for seamless switching between grid-connected and standalone modes through advanced power flow control schemes. According to scenarios of different grid/load conditions and available DG capacities in an MG, various advanced control functions can be developed for both MG operating modes: bidirectional control of active and reactive power flows, seamless switching between operating modes, improvement of grid power quality (PQ), and voltage stabilization. In this paper, mathematical models of the BTB inverter in a synchronous reference frame (SRF) is first derived, and the required controllers are then designed. For functional testing, two typical cases are simulated and analyzed in a MATLAB/Simulink environment and then verified through 1kVA small-scale hardware implementation with Texas Instruments (TI) digital signal processor (DSP) TMS320LF2812 as the control core. Results show satisfactory performances of power flow control and PQ improvement of MG. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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8 pages, 4689 KiB  
Article
Temperature-Independent Current Dispersion in 0.15 μm AlGaN/GaN HEMTs for 5G Applications
by Nicolò Zagni, Giovanni Verzellesi and Alessandro Chini
Micromachines 2022, 13(12), 2244; https://doi.org/10.3390/mi13122244 - 17 Dec 2022
Cited by 4 | Viewed by 1380
Abstract
Thanks to high-current densities and cutoff frequencies, short-channel length AlGaN/GaN HEMTs are a promising technology solution for implementing RF power amplifiers in 5G front-end modules. These devices, however, might suffer from current collapse due to trapping effects, leading to compressed output power. Here, [...] Read more.
Thanks to high-current densities and cutoff frequencies, short-channel length AlGaN/GaN HEMTs are a promising technology solution for implementing RF power amplifiers in 5G front-end modules. These devices, however, might suffer from current collapse due to trapping effects, leading to compressed output power. Here, we investigate the trap dynamic response in 0.15 μm GaN HEMTs by means of pulsed I-V characterization and drain current transients (DCTs). Pulsed I-V curves reveal an almost absent gate-lag but significant current collapse when pulsing both gate and drain voltages. The thermally activated Arrhenius process (with EA ≈ 0.55 eV) observed during DCT measurements after a short trap-filling pulse (i.e., 1 μs) indicates that current collapse is induced by deep trap states associated with iron (Fe) doping present in the buffer. Interestingly, analogous DCT characterization carried out after a long trap-filling pulse (i.e., 100 s) revealed yet another process with time constants of about 1–2 s and which was approximately independent of temperature. We reproduced the experimentally observed results with two-dimensional device simulations by modeling the T-independent process as the charging of the interface between the passivation and the AlGaN barrier following electron injection from the gate. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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10 pages, 2858 KiB  
Article
The Electrical and Thermal Characteristics of Stacked GaN MISHEMT
by Caixin Hui, Qiuqi Chen, Yijun Shi, Zhiyuan He, Yun Huang, Xiangjun Lu, Hongyue Wang, Jie Jiang and Guoguang Lu
Micromachines 2022, 13(12), 2101; https://doi.org/10.3390/mi13122101 - 28 Nov 2022
Cited by 1 | Viewed by 1003
Abstract
To study the working performance of 3D stacked chips, a double-layer stacked GaN MISHEMTs structure was designed to study the electro-thermal characteristics and heat transfer process of stacked chips. Firstly, the electrical characteristics of double-layer and single-layer GaN MISHEMTs are compared at room [...] Read more.
To study the working performance of 3D stacked chips, a double-layer stacked GaN MISHEMTs structure was designed to study the electro-thermal characteristics and heat transfer process of stacked chips. Firstly, the electrical characteristics of double-layer and single-layer GaN MISHEMTs are compared at room temperature. Under the same conditions, the output current of double-layer GaN MISHEMTs is twice that of single-layer GaN MISHEMTs, but its off-state current is much higher than that of a single-layer device. Meanwhile, there is no significant difference between the threshold voltages of the double-layer and single-layer GaN MISHEMTs. Then, the effect of temperature on the electrical characteristics of double-layer GaN MISHEMTs is also investigated. When the temperature increased from room temperature to 150 °C, the device’s threshold voltage gradually shifted negatively, the output current of the device decreased, and the off-state current of the device increased. Furthermore, a thermal resistance network model has been established to analyze the thermal characteristics of the stacked GaN MISHEMTs. The relative error between the results calculated according to the model and the experimental results does not exceed 4.26%, which verified the correctness and accuracy of the presented model to predict the temperature distribution of the stacked GaN MISHEMTs. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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16 pages, 3109 KiB  
Article
Optimal Growth Conditions for Forming c-Axis (002) Aluminum Nitride Thin Films as a Buffer Layer for Hexagonal Gallium Nitride Thin Films Produced with In Situ Continual Radio Frequency Sputtering
by Wei-Sheng Liu, Balaji Gururajan, Sui-Hua Wu, Li-Cheng Huang, Chung-Kai Chi, Yu-Lun Jiang and Hsing-Chun Kuo
Micromachines 2022, 13(9), 1546; https://doi.org/10.3390/mi13091546 - 17 Sep 2022
Cited by 3 | Viewed by 2209
Abstract
Aluminum nitride (AlN) thin-film materials possess a wide energy gap; thus, they are suitable for use in various optoelectronic devices. In this study, AlN thin films were deposited using radio frequency magnetron sputtering with an Al sputtering target and N2 as the [...] Read more.
Aluminum nitride (AlN) thin-film materials possess a wide energy gap; thus, they are suitable for use in various optoelectronic devices. In this study, AlN thin films were deposited using radio frequency magnetron sputtering with an Al sputtering target and N2 as the reactive gas. The N2 working gas flow rate was varied among 20, 30, and 40 sccm to optimize the AlN thin film growth. The optimal AlN thin film was produced with 40 sccm N2 flow at 500 W under 100% N2 gas and at 600 °C. The films were studied using X-ray diffraction and had (002) phase orientation. X-ray photoelectron spectroscopy was used to determine the atomic content of the optimal film to be Al, 32%; N, 52%; and O, 12% at 100 nm beneath the surface of the thin film. The film was also investigated through atomic force microscopy and had a root mean square roughness of 2.57 nm and a hardness of 76.21 GPa. Finally, in situ continual sputtering was used to produce a gallium nitride (GaN) layer on Si with the AlN thin film as a buffer layer. The AlN thin films investigated in this study have excellent material properties, and the proposed process could be a less expensive method of growing high-quality GaN thin films for various applications in GaN-based power transistors and Si integrated circuits. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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8 pages, 1306 KiB  
Article
Boron Nitride Nanoribbons Grown by Chemical Vapor Deposition for VUV Applications
by Jiandong Hao, Ling Li, Peng Gao, Xiangqian Jiang, Chuncheng Ban and Ningqiang Shi
Micromachines 2022, 13(9), 1372; https://doi.org/10.3390/mi13091372 - 23 Aug 2022
Cited by 3 | Viewed by 1202
Abstract
The fabrication process of vacuum ultraviolet (VUV) detectors based on traditional semiconductor materials is complex and costly. The new generation of wide-bandgap semiconductor materials greatly reduce the fabrication cost of the entire VUV detector. We use the chemical vapor deposition (CVD) method to [...] Read more.
The fabrication process of vacuum ultraviolet (VUV) detectors based on traditional semiconductor materials is complex and costly. The new generation of wide-bandgap semiconductor materials greatly reduce the fabrication cost of the entire VUV detector. We use the chemical vapor deposition (CVD) method to grow boron nitride nanoribbons (BNNRs) for VUV detectors. Morphological and compositional characterization of the BNNRs was tested. VUV detector based on BNNRs exhibits strong response to VUV light with wavelengths as short as 185 nm. The photo–dark current ratio (PDCR) of this detector is 272.43, the responsivity is 0.47 nA/W, and the rise time and fall time are 0.3 s and 0.6 s. The response speed is faster than the same type of BN-based VUV detectors. This paper offers more opportunities for high-performance and low-cost VUV detectors made of wide-bandgap semiconductor materials in the future. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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14 pages, 4442 KiB  
Article
Impact of Generation and Relocation of Defects on Optical Degradation of Multi-Quantum-Well InGaN/GaN-Based Light-Emitting Diode
by Claudia Casu, Matteo Buffolo, Alessandro Caria, Carlo De Santi, Enrico Zanoni, Gaudenzio Meneghesso and Matteo Meneghini
Micromachines 2022, 13(8), 1266; https://doi.org/10.3390/mi13081266 - 06 Aug 2022
Cited by 2 | Viewed by 1432
Abstract
The defectiveness of InGaN-based quantum wells increases with low indium contents, due to the compressive strain induced by the lattice mismatch between the InGaN and GaN layers, and to the stronger incorporation of defects favored by the presence of indium. Such defects can [...] Read more.
The defectiveness of InGaN-based quantum wells increases with low indium contents, due to the compressive strain induced by the lattice mismatch between the InGaN and GaN layers, and to the stronger incorporation of defects favored by the presence of indium. Such defects can limit the performance and the reliability of LEDs, since they can act as non-radiative recombination centers, and favor the degradation of neighboring semiconductor layers. To investigate the location of the layers mostly subjected to degradation, we designed a color-coded structure with two quantum wells having different indium contents. By leveraging on numerical simulations, we explained the experimental results in respect of the ratio between the emissions of the two main peaks as a function of current. In addition, to evaluate the mechanisms that limit the reliability of this type of LED, we performed a constant-current stress test at high temperature, during which we monitored the variation in the optical characteristics induced by degradation. By comparing experimental and simulated results, we found that degradation can be ascribed to an increment of traps in the active region. This process occurs in two different phases, with different rates for the two quantum wells. The first phase mainly occurs in the quantum well closer to the p-contact, due to an increment of defectiveness. Degradation follows an exponential trend, and saturates during the second phase, while the quantum well close to the n-side is still degrading, supporting the hypothesis of the presence of a diffusive front that is moving from the p-side towards the n-side. The stronger degradation could be related to a lowering of the injection efficiency, or an increment of SRH recombination driven by a recombination-enhanced defect generation process. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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11 pages, 6329 KiB  
Article
Normally-off β-Ga2O3 MOSFET with an Epitaxial Drift Layer
by Chan-Hee Jang, Gökhan Atmaca and Ho-Young Cha
Micromachines 2022, 13(8), 1185; https://doi.org/10.3390/mi13081185 - 27 Jul 2022
Cited by 3 | Viewed by 1755
Abstract
A normally-off β-Ga2O3 metal-oxide-semiconductor field-effect transistor (MOSFET) is proposed using a technology computer-aided design (TCAD) device simulation, which employs an epitaxial drift layer grown on an n-type low-doped body layer. The low-doped body layer under the MOS gate enabled [...] Read more.
A normally-off β-Ga2O3 metal-oxide-semiconductor field-effect transistor (MOSFET) is proposed using a technology computer-aided design (TCAD) device simulation, which employs an epitaxial drift layer grown on an n-type low-doped body layer. The low-doped body layer under the MOS gate enabled normally-off operation, whereas the epitaxial drift layer determined the on-resistance and breakdown characteristics. The effects of the doping concentration of each layer and thickness of the drift channel layer on the device characteristics were investigated to design a device with a breakdown voltage of 1 kV. A threshold voltage of 1.5 V and a breakdown voltage of 1 kV were achieved by an n-type body layer with a doping concentration of 1 × 1015 cm−3 and an n-type drift layer with a doping concentration of 3 × 1017 cm−3, a thickness of 150 nm, and a gate-to-drain distance of 9.5 μm; resulting in an on-resistance of 25 mΩ·cm2. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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11 pages, 3628 KiB  
Article
An AlGaN/GaN Lateral Bidirectional Current-Regulating Diode with Two Symmetrical Hybrid Ohmic-Schottky Structures
by Yijun Shi, Zongqi Cai, Yun Huang, Zhiyuan He, Yiqiang Chen, Liye Cheng and Guoguang Lu
Micromachines 2022, 13(7), 1157; https://doi.org/10.3390/mi13071157 - 21 Jul 2022
Viewed by 1173
Abstract
Bidirectional current-regulating ability is needed for AC light emitting diode (LED) drivers. In previous studies, various rectifier circuits have been used to provide constant bidirectional current. However, the usage of multiple electronic components can lead to additional costs and power consumption. In this [...] Read more.
Bidirectional current-regulating ability is needed for AC light emitting diode (LED) drivers. In previous studies, various rectifier circuits have been used to provide constant bidirectional current. However, the usage of multiple electronic components can lead to additional costs and power consumption. In this work, a novel AlGaN/GaN lateral bidirectional current-regulating diode (B-CRD) featuring two symmetrical hybrid-trench electrodes is proposed and demonstrated by TCAD Sentaurus (California USA) from Synopsys corporation. Through shortly connecting the Ohmic contact and trench Schottky contact, the unidirectional invariant current can be obtained even with the applied voltage spanning a large range of 0–200 V. Furthermore, with the combination of two symmetrical hybrid-trench electrodes at each side of the device, the proposed B-CRD can deliver an excellent steady current in different directions. Through the TCAD simulation results, it was found that the device’s critical characteristics (namely knee voltage and current density) can be flexibly modulated by tailoring the depth and length of the trench Schottky contact. Meanwhile, it was also demonstrated through the device/circuit mixed-mode simulation that the proposed B-CRD can respond to the change in voltage in a few nanoseconds. Such a new functionality combined with excellent performance may make the proposed B-CRD attractive in some special fields where the bidirectional current-limiting function is needed. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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10 pages, 5652 KiB  
Article
A Wideband High-Efficiency GaN MMIC Power Amplifier for Sub-6-GHz Applications
by Liulin Hu, Xuejie Liao, Fan Zhang, Haifeng Wu, Shenglin Ma, Qian Lin and Xiaohong Tang
Micromachines 2022, 13(5), 793; https://doi.org/10.3390/mi13050793 - 20 May 2022
Cited by 4 | Viewed by 3272
Abstract
The monolithic microwave integrated circuit (MMIC) power amplifiers serve an essential and critical role in RF transmit/receive (T/R) modules of phased array radar systems, mobile communication systems and satellite systems. Over recent years, there has been an increasing requirement to develop wideband high-efficiency [...] Read more.
The monolithic microwave integrated circuit (MMIC) power amplifiers serve an essential and critical role in RF transmit/receive (T/R) modules of phased array radar systems, mobile communication systems and satellite systems. Over recent years, there has been an increasing requirement to develop wideband high-efficiency MMIC high power amplifiers (HPAs) to accommodate wideband operation and reduce power consumption. This paper presents a wideband high efficiency MMIC HPA for Sub-6-GHz applications using a 0.25-μm gate-length D-mode GaN/SiC high electron mobility transistor (HEMT) process. The amplifier consists of two stages with two HEMT cells for the driver stage and eight HEMT cells for the power stage. To obtain a flat gain while maintaining the wideband characteristic, a gain equalization technique is employed in the inter-stage matching circuit. Meanwhile, a low-loss output matching network is utilized to ensure high efficiency. The fabricated HPA occupies a compact chip area of 14.35 mm2 including testing pads. Over the frequency range of 2–6 GHz, measured results of this HPA show a saturated continuous wave (CW) output power of 44.4–45.2 dBm, a power added efficiency (PAE) of 35.8–51.3%, a small signal gain of 24–25.5 dB, and maximum input and output return losses of 14.5 and 10 dB, respectively. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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8 pages, 8199 KiB  
Article
Investigation on the Thermal Characteristics of Enhancement-Mode p-GaN HEMT Device on Si Substrate Using Thermoreflectance Microscopy
by Hongyue Wang, Chao Yuan, Yajie Xin, Yijun Shi, Yaozong Zhong, Yun Huang and Guoguang Lu
Micromachines 2022, 13(3), 466; https://doi.org/10.3390/mi13030466 - 18 Mar 2022
Cited by 5 | Viewed by 2309
Abstract
In this paper, thermoreflectance microscopy was used to measure the high spatial resolution temperature distribution of the p-GaN HEMT under high power density. The maximum temperature along the GaN channel was located at the drain-side gate edge region. It was found that the [...] Read more.
In this paper, thermoreflectance microscopy was used to measure the high spatial resolution temperature distribution of the p-GaN HEMT under high power density. The maximum temperature along the GaN channel was located at the drain-side gate edge region. It was found that the thermal resistance (Rth) of the p-GaN HEMT device increased with the increase of channel temperature. The Rth dependence on the temperature was well approximated by a function of Rth~Ta (a = 0.2). The three phonon Umklapp scattering, point mass defects and dislocations scattering mechanisms are suggested contributors to the heat transfer process for the p-GaN HEMT. The impact of bias conditions and gate length on the thermal characteristics of the device was investigated. The behaviour of temperature increasing in the time domain with 50 µs pulse width and different drain bias voltage was analysed. Finally, a field plate structure was demonstrated for improving the device thermal performance. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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9 pages, 3523 KiB  
Article
A Novel AlGaN/GaN Transient Voltage Suppression Diode with Bidirectional Clamp Capability
by Zhiyuan He, Yijun Shi, Yun Huang, Yiqiang Chen, Hongyue Wang, Lei Wang, Guoguang Lu and Yajie Xin
Micromachines 2022, 13(2), 299; https://doi.org/10.3390/mi13020299 - 14 Feb 2022
Cited by 4 | Viewed by 1919
Abstract
This work proposes a novel AlGaN/GaN transient voltage suppression (TVS) diode (B-TVS-D) with bidirectional clamp capability, which consists of a small-size AlGaN/GaN monolithic bidirectional switch, two 2DEG-based current-limiting resistors (R1A/R1C, in parallel connection between the gate electrodes [...] Read more.
This work proposes a novel AlGaN/GaN transient voltage suppression (TVS) diode (B-TVS-D) with bidirectional clamp capability, which consists of a small-size AlGaN/GaN monolithic bidirectional switch, two 2DEG-based current-limiting resistors (R1A/R1C, in parallel connection between the gate electrodes and the neighboring ohmic-contact electrodes (anode/cathode)), and a 2DEG-based proportional amplification resistor (R2, in parallel connection between two gate electrodes). It is demonstrated that the proposed B-TVS-D possesses a symmetrical triggering voltage (Vtrig) and a high secondary breakdown current (Is, over 8 A, corresponding to 12 kV human body model failure voltage) in different directional electrostatic discharge (ESD) events. The proposed diode can effectively enhance the electrostatic discharge robustness for the GaN-based power system. It is also verified that R1A/R1C and R2 have an important impact on Vtrig of the proposed B-TVS-D. Both the decrease in R2 and increase in R1A/R1C can lead to the decrease of Vtrig. In addition, the proposed B-TVS-D can be fabricated on the conventional p-GaN HEMT platform, making the ESD design of the GaN-based power system more convenient. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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11 pages, 2455 KiB  
Article
Resonant Raman Scattering in Boron-Implanted GaN
by Yi Peng, Wenwang Wei, Muhammad Farooq Saleem, Kai Xiao, Yanlian Yang, Yufei Yang, Yukun Wang and Wenhong Sun
Micromachines 2022, 13(2), 240; https://doi.org/10.3390/mi13020240 - 31 Jan 2022
Cited by 1 | Viewed by 2220
Abstract
A small Boron ion (B-ion) dose of 5 × 1014 cm−2 was implanted in a GaN epilayer at an energy of 50 keV, and the sample was subjected to high-temperature rapid thermal annealing (RTA). The resonant Raman spectrum (RRS) showed a [...] Read more.
A small Boron ion (B-ion) dose of 5 × 1014 cm−2 was implanted in a GaN epilayer at an energy of 50 keV, and the sample was subjected to high-temperature rapid thermal annealing (RTA). The resonant Raman spectrum (RRS) showed a strong characteristic of a photoluminescence (PL) emission peak associated with GaN before B-ion implantation and RTA treatment. The PL signal decreased significantly after the B-ion implantation and RTA treatment. The analysis of temperature-dependent Raman spectroscopy data indicated the activation of two transitions in B-ion-implanted GaN in different temperature ranges with activation energies of 66 and 116 meV. The transition energies were estimated in the range of 3.357–3.449 eV through calculations. This paper introduces a calculation method that can be used to calculate the activation and transition energies, and it further highlights the strong influence of B-ion implantation on the luminesce of GaN. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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Review

Jump to: Research

36 pages, 6200 KiB  
Review
Challenges and Opportunities for High-Power and High-Frequency AlGaN/GaN High-Electron-Mobility Transistor (HEMT) Applications: A Review
by Muhaimin Haziq, Shaili Falina, Asrulnizam Abd Manaf, Hiroshi Kawarada and Mohd Syamsul
Micromachines 2022, 13(12), 2133; https://doi.org/10.3390/mi13122133 - 01 Dec 2022
Cited by 15 | Viewed by 7990
Abstract
The emergence of gallium nitride high-electron-mobility transistor (GaN HEMT) devices has the potential to deliver high power and high frequency with performances surpassing mainstream silicon and other advanced semiconductor field-effect transistor (FET) technologies. Nevertheless, HEMT devices suffer from certain parasitic and reliability concerns [...] Read more.
The emergence of gallium nitride high-electron-mobility transistor (GaN HEMT) devices has the potential to deliver high power and high frequency with performances surpassing mainstream silicon and other advanced semiconductor field-effect transistor (FET) technologies. Nevertheless, HEMT devices suffer from certain parasitic and reliability concerns that limit their performance. This paper aims to review the latest experimental evidence regarding HEMT technologies on the parasitic issues that affect aluminum gallium nitride (AlGaN)/GaN HEMTs. The first part of this review provides a brief introduction to AlGaN/GaN HEMT technologies, and the second part outlines the challenges often faced during HEMT fabrication, such as normally-on operation, self-heating effects, current collapse, peak electric field distribution, gate leakages, and high ohmic contact resistance. Finally, a number of effective approaches to enhancing the device’s performance are addressed. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
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