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14 pages, 5908 KB

Open AccessArticle

V_TH-Adjustable p-Channel GaN Field-Effect Transistor with an Inserted n-GaN Layer

by Yuheng Liu, Tao Zhang, Huake Su, Jiahao Chen, Xiangdong Li, Shengrui Xu, Zeyang Ren, Weidong Zhu, Yu Du, Yue Hao and Jincheng Zhang

Micromachines 2026, 17(8), 913; https://doi.org/10.3390/mi17080913 - 29 Jul 2026

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Abstract

In this work, a novel Schottky-gated p-channel GaN field-effect transistor (PFET) with a tunable n-GaN sub-gate layer is investigated. Terminal-current analysis under the actual drain-bias condition shows that the gate-current contribution remains limited within the defined effective operating range of V_GS ≥ −3.2 V, whereas gate-related current becomes significant at more negative gate biases. Carrier-resolved and spatial current analyses further confirm that, within this operating range, the drain current is predominantly carried by holes through an interfacial hole channel near the p-GaN/AlGaN heterointerface. Benefiting from the intentionally introduced p–n junction beneath the groove gate, the built-in electric field effectively depletes the p-GaN channel, enabling a robust transition from depletion-mode to enhancement-mode (E-mode) operation. By precisely scaling the n-GaN layer thickness (0–5 nm) and donor concentration (3.0 × 10¹⁷ cm⁻³ to 3.0 × 10¹⁹ cm⁻³), the buried p-n junction modulates the depletion condition and hole distribution beneath the gate. The optimized device exhibits a significantly improved subthreshold swing (SS) of 348 mV/dec, while maintaining a stable I_ON/I_OFF ratio on the order of 10². This tunable sub-gate architecture provides a highly flexible platform for optimizing E-mode GaN PFETs, showing great promise for high-performance complementary logic applications. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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13 pages, 1463 KB

Open AccessArticle

Weak-Light-Enhanced AlGaN/GaN UV Phototransistors with a Buried p-GaN Structure

by Haiping Wang, Feiyu Zhang, Xuzhi Zhao, Haifan You, Zhan Ma, Jiandong Ye, Hai Lu, Rong Zhang, Youdou Zheng and Dunjun Chen

Electronics 2025, 14(10), 2076; https://doi.org/10.3390/electronics14102076 - 20 May 2025

Cited by 5 | Viewed by 1881

Abstract

We propose a novel ultraviolet (UV) phototransistor (PT) architecture based on an AlGaN/GaN high electron mobility transistor (HEMT) with a buried p-GaN layer. In the dark, the polarization-induced two-dimensional electron gas (2DEG) at the AlGaN/GaN heterojunction interface is depleted by the buried p-GaN and the conduction channel is closed. Under UV illumination, the depletion region shrinks to just beneath the AlGaN/GaN interface and the 2DEG recovers. The retraction distance of the depletion region during device turn-on operation is comparable to the thickness of the AlGaN barrier layer, which is an order of magnitude smaller than that in the conventional p-GaN/AlGaN/GaN PT, whose retraction distance spans the entire GaN channel layer. Consequently, the proposed device demonstrates significantly enhanced weak-light detection capability and improved switching speed. Silvaco Atlas simulations reveal that under a weak UV intensity of 100 nW/cm², the proposed device achieves a photocurrent density of 1.68 × 10⁻³ mA/mm, responsivity of 8.41 × 10⁵ A/W, photo-to-dark-current ratio of 2.0 × 10⁸, UV-to-visible rejection ratio exceeding 10⁸, detectivity above 1 × 10¹⁹ cm·Hz^1/2/W, and response time of 0.41/0.41 ns. The electron concentration distributions, conduction band variations, and 2DEG recovery behaviors in both the conventional and novel structures under dark and weak UV illumination are investigated in depth via simulations. Full article

(This article belongs to the Special Issue Advances in Semiconductor GaN and Applications)

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10 pages, 4095 KB

Open AccessArticle

Improvement of Single Event Transient Effects for a Novel AlGaN/GaN High Electron-Mobility Transistor with a P-GaN Buried Layer and a Locally Doped Barrier Layer

by Juan Xiong, Xintong Xie, Jie Wei, Shuxiang Sun and Xiaorong Luo

Micromachines 2024, 15(9), 1158; https://doi.org/10.3390/mi15091158 - 16 Sep 2024

Cited by 11 | Viewed by 2928

Abstract

In this paper, a novel AlGaN/GaN HEMT structure with a P-GaN buried layer in the buffer layer and a locally doped barrier layer under the gate (PN-HEMT) is proposed to enhance its resistance to single event transient (SET) effects while also overcoming the degradation of other characteristics. The device operation mechanism and characteristics are investigated by TCAD simulation. The results show that the peak electric field and impact ionization at the gate edges are reduced in the PN-HEMT due to the introduced P-GaN buried layer in the buffer layer. This leads to a decrease in the peak drain current (I_peak) induced by the SET effect and an improvement in the breakdown voltage (BV). Additionally, the locally doped barrier layer provides extra electrons to the channel, resulting in higher saturated drain current (I_D,sat) and maximum transconductance (g_max). The I_peak of the PN-HEMT (1.37 A/mm) is 71.8% lower than that of the conventional AlGaN/GaN HEMT (C-HEMT) (4.85 A/mm) at 0.6 pC/µm. Simultaneously, I_D,sat and BV are increased by 21.2% and 63.9%, respectively. Therefore, the PN-HEMT enhances the hardened SET effect of the device without sacrificing other key characteristics of the AlGaN/GaN HEMT. Full article

(This article belongs to the Special Issue Advances in GaN- and SiC-Based Electronics: Design and Applications)

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12 pages, 6900 KB

Open AccessArticle

Effect of P-Type GaN Buried Layer on the Temperature of AlGaN/GaN HEMTs

by Hanghang Lv, Yanrong Cao, Maodan Ma, Zhiheng Wang, Xinxiang Zhang, Chuan Chen, Linshan Wu, Ling Lv, Xuefeng Zheng, Yongkun Wang, Wenchao Tian and Xiaohua Ma

Micromachines 2023, 14(7), 1457; https://doi.org/10.3390/mi14071457 - 20 Jul 2023

Cited by 14 | Viewed by 2817

Abstract

In this paper, a P-type GaN buried layer is introduced into the buffer layer of AlGaN/GaN HEMTs, and the effect of the P-type GaN buried layer on the device’s temperature characteristics is studied using Silvaco TCAD software. The results show that, compared to the conventional device structure, the introduction of a P-type GaN buried layer greatly weakens the peak of the channel electric field between the gate and drain of the device. This leads to a more uniform electric field distribution, a substantial reduction in the lattice temperature of the device, and a more uniform temperature distribution. Therefore, the phenomenon of negative resistance caused by self-heating effect is significantly mitigated, while the breakdown performance of the device is also notably enhanced. Full article

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11 pages, 3236 KB

Open AccessArticle

Vertical Integration of Nitride Laser Diodes and Light Emitting Diodes by Tunnel Junctions

by Marcin Siekacz, Grzegorz Muziol, Henryk Turski, Mateusz Hajdel, Mikolaj Żak, Mikolaj Chlipała, Marta Sawicka, Krzesimir Nowakowski-Szkudlarek, Anna Feduniewicz-Żmuda, Julita Smalc-Koziorowska, Szymon Stańczyk and Czeslaw Skierbiszewski

Electronics 2020, 9(9), 1481; https://doi.org/10.3390/electronics9091481 - 10 Sep 2020

Cited by 20 | Viewed by 4799

Abstract

We demonstrate the applications of tunnel junctions (TJs) for new concepts of monolithic nitride-based multicolor light emitting diode (LED) and laser diode (LD) stacks. The presented structures were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN bulk crystals. We demonstrate a stack of four LDs operated at pulse mode with emission wavelength of 453 nm. The output power of 1.1 W and high slope efficiency of 2.3 W/A is achieved for devices without dielectric mirrors. Atomically flat surface after the epitaxy of four LD stack and low dislocation density is measured as a result of proper TJ design with optimized doping level. The strain compensation design with InGaN waveguides and AlGaN claddings is shown to be crucial to avoid cracking and lattice relaxation of the 5 µm thick structure. Vertical connection of n-LDs allows for cascade emission of photons and increases the quantum efficiency n-times. The two-color (blue and green) LEDs are demonstrated. Application of TJs simplifies device processing, reducing the need for applications of p-type contact. The key factor enabling demonstration of such devices is hydrogen-free PAMBE technology, in which activation of buried p-type layers is not necessary. Full article

(This article belongs to the Special Issue Micro- and Nanotechnology of Wide Bandgap Semiconductors)

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