Device Characteristics of E-mode GaN HEMTs with a Second Gate Connected to the Source
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https://doi.org/10.1007/s11664-020-08292-7 2020 The Minerals, Metals & Materials Society
INTERNATIONAL ELECTRON DEVICES AND MATERIALS SYMPOSIUM 2019
Device Characteristics of E-mode GaN HEMTs with a Second Gate Connected to the Source CHIH-WEI CHEN,1 WEI-CHEN HO,1 YUE-MING HSIN ,1,2,4 JERRY TZOU,3 WEN-HSIEN HUANG,3 CHANG-HONG SHEN,3 JIA-MING SHIEH,3 WEN-KUAN YEH,3 WEN-TA HSU,3 and SZE-CHING LIU3 1.—Department of Electrical Engineering, National Central University, Taoyuan City 32001, Taiwan. 2.—Optical Science Center, National Central University, Taoyuan City 32001, Taiwan. 3.—Taiwan Semiconductor Research Institute (TSRI), Hsinchu 30078, Taiwan. 4.—e-mail: [email protected]
In this study, the device characteristics of dual-gate GaN high-electron-mobility transistors (HEMTs) were determined. The research investigated an enhancement-mode (E-mode) GaN HEMT with a second gate connected to the source and located between the main gate and drain. Two dual-gate GaN HEMTs with different second-gate designs, using Schottky or metal–insulator–semiconductor (MIS) contacts, were simulated and fabricated, and the direct current of the devices was investigated. In device simulation, p-GaN gates were used to achieve E-mode operation in HEMTs. Technology computer-aided design (TCAD) simulation indicated that the saturation drain current (ID, sat) of devices with Schottky and MIS second gates was 88% and 38% lower than that of a single gate structure, while increasing on resistance (Ron) by 31% and 8%, respectively. In device fabrication, a Schottky and MIS second gate were respectively added to an E-mode p-GaN gate HEMT and an E-mode recesses-gate GaN MIS-HEMT. Compared with single-gate structures, the devices with a Schottky and MIS second gates reduced ID, sat by 75% and 32%, respectively, while increasing Ron by 25% and 6%, respectively. The measured electrical characteristics indicate the same trend obtained from TCAD simulation: The dual-gate design can improve the short-circuit capability of GaN HEMTs by reducing the ID, sat under on-state and high-current conditions. Key words: AlGaN/GaN, enhancement mode, p-GaN gate, gate recess, short circuit, second gate
INTRODUCTION GaN-based materials are considered promising for high-power and high-frequency electronics because GaN exhibits excellent properties, such as higher electric breakdown field and electron mobility than Si. However, AlGaN/GaN high-electronmobility transistors (HEMTs) are depletion-mode
(Received December 4, 2019; accepted June 19, 2020)
(D-mode) devices because a high concentration of a two-dimensional electron gas (2DEG) forms at the AlGaN/GaN interface. In power-switching applications of GaN HEMTs, a normally off operation is required for safe operation and circuit design. Several approaches, including using a p-GaN gate, gate recessing, fluorine ion implantation, and a three-dimensional (3D) fin field-effect transistor structure, have been employed to obtain enhancement-mode (E-mode) HEMTs.1–3 The p-GaN gate is the most promising because of its st
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