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Micromachines
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GaN-Based Materials and Devices: Research and Applications, 2nd Edition
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GaN-Based Materials and Devices: Research and Applications, 2nd Edition

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

Deadline for manuscript submissions: 30 June 2026 | Viewed by 1855

Special Issue Editors

Dr. Wei Liu

E-Mail Website
Guest Editor
School of Microelectronics, Northwestern Polytechnical University, Xi’an 710129, China
Interests: GaN; GaAs; optoelectronic technology; device modeling; LED/LD/APD; solar cell; performance characterization
Special Issues, Collections and Topics in MDPI journals
Dr. Kun Wang

E-Mail Website
Guest Editor
School of Microelectronics, Northwestern Polytechnical University, Xi'an, China
Interests: semiconductor materials; semiconductor devices; solar cells; light-emitting diodes; photodetectors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wurtzite III-nitrides semiconductor materials, represented by GaN, have been widely used in high-frequency, high-power, and optoelectronic devices due to their excellent electrical and optical properties. For example, their superior electron mobility and wide bandgap make them highly promising candidates for high-frequency and high-power electronic devices. Furthermore, their direct and tunable bandgap have made them attractive for various optoelectronic applications, such as light-emitting diodes (LEDs), laser diodes (LDs), sensors, and photovoltaic cells. However, the potential of GaN-based devices is still far from being fully developed. The challenges exist in many aspects, such as the poor material quality, unstable fabrication process, and thermal management. Therefore, by leveraging the intriguing properties of (Al,In)GaN compound semiconductors, researchers and engineers may develop devices with improved performance, benefiting various aspects of our daily lives.  

This Special Issue, titled "GaN-based Materials and Devices: Research and Applications", of the Journal Micromachines aims to present recent advantages in the design, growth, fabrication, characterization, and simulation of GaN-based compound semiconductors, as well as their related electronic and optoelectronic devices. The scope of this Special Issue includes, but is not limited to, the following:

  • Epitaxial growth, fabrication, and characterization techniques for state-of-the-art AlInGaN alloys and their semiconductor heterostructures;
  • Research on the physical, chemical, electronic, and optical properties of GaN-based materials and devices for various applications;
  • Novel concepts for device structure design;
  • Advanced simulation or modeling for GaN-based electronic and optoelectronic devices.

We look forward to receiving your submissions to this Special Issue.

Dr. Wei Liu
Dr. Kun Wang
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 2100 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

  • group III-nitrides semiconductors
  • epitaxial growth and fabrication
  • Al(In)GaN heterostructure
  • polarization and piezoelectric effect
  • nanostructures for wide bandgap materials
  • RF and power devices
  • display and illumination applications
  • novel design concepts
  • device simulation

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Related Special Issue

Published Papers (5 papers)

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Research

12 pages, 1488 KB  
Article
Gate Metal Defect Screening at Wafer-Level for Improvement of HTGB in Power GaN HEMT
by Yu-Ting Chuang and Niall Tumilty
Micromachines 2025, 16(11), 1260; https://doi.org/10.3390/mi16111260 - 6 Nov 2025
Abstract
The increasing market demand for high-power and high-frequency applications necessitates the development of highly reliable Gallium Nitride (GaN) High-Electron-Mobility Transistors (HEMTs). While GaN offers superior performance and efficiency over traditional silicon, gate-related defects pose a significant reliability challenge, often leading to premature device [...] Read more.
The increasing market demand for high-power and high-frequency applications necessitates the development of highly reliable Gallium Nitride (GaN) High-Electron-Mobility Transistors (HEMTs). While GaN offers superior performance and efficiency over traditional silicon, gate-related defects pose a significant reliability challenge, often leading to premature device failure under stress. Traditional High-Temperature Gate Bias (HTGB) testing is effective but time-consuming and costly, particularly when defects are only identified post-packaging. This study focuses on developing an effective wafer-level screening methodology to mitigate the financial burden and reputational risk associated with late-stage defect discovery. Failure analysis of an HTGB premature failure revealed a gate metal deposition defect characterized by identical elemental composition to the bulk metal, suggesting a small-volume structural anomaly. Crucially, a comparative analysis showed that Forward Gate Current (IGON) is an insensitive screening metric due to high inherent gate leakage through the passivation layer. In contrast, the Reverse Gate Current (IGOFF) exhibited sensitivity, particularly under the tensile stress induced by package molding, which is attributed to the piezoelectric effect altering the depletion region width beneath the p-GaN gate. Based on this observation, a multi-pulse IDSS test was developed as a wafer-level screen. This method successfully amplified the subtle electrical field perturbations caused by the gate defect. After screening 231 dies using the new methodology, zero failures were recorded after 1000 h of HTGB stress, a significant improvement over the initial failure rate of 0.43% (1 out of 231). This work demonstrates that early, sensitive wafer-level screening of gate defects is indispensable for optimizing manufacturing yield and enhancing long-term device reliability. Full article
(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)
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9 pages, 2943 KB  
Article
Improve Intermetal Dielectric Process for HTRB Stability in Power GaN High Electron Mobility Transistor (HEMT) by unbiased-Highly Accelerated Stress Testing (uHAST)
by Yu-Ting Chuang, Niall Tumilty and Tian-Li Wu
Micromachines 2025, 16(11), 1233; https://doi.org/10.3390/mi16111233 - 30 Oct 2025
Viewed by 306
Abstract
This study investigates a severe high-temperature reverse bias (HTRB) failure observed in GaN HEMTs, with devices failing in under 24 h. We conducted an in-depth analysis of the electrical and physical failure mechanisms, revealing that unbiased-highly accelerated stress testing (uHAST) can effectively induce [...] Read more.
This study investigates a severe high-temperature reverse bias (HTRB) failure observed in GaN HEMTs, with devices failing in under 24 h. We conducted an in-depth analysis of the electrical and physical failure mechanisms, revealing that unbiased-highly accelerated stress testing (uHAST) can effectively induce dielectric delamination. The electrical and physical characteristics of devices post-delamination demonstrated a strong correlation between delamination at the nitride–polyimide interface and an increase in off-state drain leakage current (IDSS). Our findings led to the removal of a suspected process step involving the use of the reactive chemical, N-methyl-2-pyrrolidone (NMP), before and after polyimide deposition. This critical process change yielded a significant improvement in reliability; while the initial failure rate was 25% at 24 h, three lots of 260 parts subsequently survived 1000 h of HTRB stress with no failure. In conclusion, uHAST is a valuable reliability testing tool for assessing package and film adhesion, leveraging high pressure and moisture to quickly identify and troubleshoot delamination-related reliability issues. Full article
(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)
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11 pages, 2907 KB  
Article
Electrical Characterization and Simulation of GaN-on-Si Pseudo-Vertical MOSFETs with Frequency-Dependent Gate C–V Investigation
by Valentin Ackermann, Mohammed El Amrani, Blend Mohamad, Riadh Ben Abbes, Matthew Charles, Sebastien Cavalaglio, Manuel Manrique, Julien Buckley and Bassem Salem
Micromachines 2025, 16(11), 1193; https://doi.org/10.3390/mi16111193 - 22 Oct 2025
Viewed by 467
Abstract
This work presents a comprehensive study of GaN-on-Si pseudo-vertical MOSFETs focusing on single-trench and multi-trench designs. Thanks to a gate-first process flow based on an Al2O3/TiN MOS stack, both fabricated devices exhibit promising transistor behavior, with steady normally OFF [...] Read more.
This work presents a comprehensive study of GaN-on-Si pseudo-vertical MOSFETs focusing on single-trench and multi-trench designs. Thanks to a gate-first process flow based on an Al2O3/TiN MOS stack, both fabricated devices exhibit promising transistor behavior, with steady normally OFF operation, very low gate leakage current, and good switching performance. Following the extraction of a low effective channel mobility, the frequency dependence of gate-to-source C–V characteristics is studied. In addition, using TCAD Sentaurus Synopsys simulations, the impact of positive fixed charge and donor-type defects at the p-GaN/dielectric interface is investigated, together with the frequency dependency. Finally, by comparing experimental and simulated results, a mechanism is proposed linking the observed threshold voltage shift to the presence of sharp trench-bottom micro-trenching. This mechanism may further explain the origin of the additional C–V hump observed at high frequencies, which could arise from charge trapping at the p-GaN/dielectric interface or from charge inversion in the p-GaN region. Full article
(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)
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14 pages, 2529 KB  
Article
Effects of Switching on the 2-DEG Channel in Commercial E-Mode GaN-on-Si HEMT
by Roberto Baca-Arroyo
Micromachines 2025, 16(10), 1173; https://doi.org/10.3390/mi16101173 - 16 Oct 2025
Viewed by 366
Abstract
In this study, the effects of switching on the two-dimensional electron gas (2-DEG) channel in an E-mode GaN-on-Si HEMT are investigated using a GS-065-004-1-L device that is commercially available for educational practice. A practical prototype with a reduced number of components is proposed, [...] Read more.
In this study, the effects of switching on the two-dimensional electron gas (2-DEG) channel in an E-mode GaN-on-Si HEMT are investigated using a GS-065-004-1-L device that is commercially available for educational practice. A practical prototype with a reduced number of components is proposed, with empirical concepts used to explain its predictive performance when a coreless transformer is series-connected to the E-mode GaN-on-Si HEMT for switching-mode conduction. Conduction modes arising at the p-GaN/n-AlGaN/i-GaN heterojunction in accordance with specifications from the manufacturer’s datasheet were validated using a didactic physical-based model dependent on semiconductor parameters of gallium nitride (GaN). Test circuit-examined waveforms were analyzed, which confirmed that the switching conduction mode of the 2-DEG channel is dependent on physical parameters such as switching operating frequency, temperature, low-field electron mobility, and space charge capacitance. Full article
(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)
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10 pages, 895 KB  
Article
Investigation on the Carrier Dynamics in P-I-N Type Photovoltaic Devices with Different Step-Gradient Distribution of Indium Content in the Intrinsic Region
by Yifan Song, Wei Liu, Junjie Gao, Di Wang, Chengrui Yan, Bohan Shi, Linyuan Zhang, Xinnan Zhao and Zeyu Liu
Micromachines 2025, 16(7), 833; https://doi.org/10.3390/mi16070833 - 21 Jul 2025
Viewed by 426
Abstract
InGaN-based photovoltaic devices have attracted great attention due to their remarkable theoretical potential for high efficiency. In this paper, the influence of different distributions of step-gradient indium content within the intrinsic region on the photovoltaic performance of P-I-N type InGaN/GaN solar cells is [...] Read more.
InGaN-based photovoltaic devices have attracted great attention due to their remarkable theoretical potential for high efficiency. In this paper, the influence of different distributions of step-gradient indium content within the intrinsic region on the photovoltaic performance of P-I-N type InGaN/GaN solar cells is numerically investigated. Through the comprehensive analysis of carrier dynamics, it is found that for the device with the indium content decreasing stepwise from 50% at the top to 10% at the bottom in intrinsic region, the photovoltaic conversion efficiency is increased to 10.29%, which can be attributed to joint influence of enhanced photon absorption, reduced recombination rate, and optimized carrier transport process. Full article
(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)
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