Device Characteristics of E-mode GaN HEMTs with a Second Gate Connected to the Source

Chih Wei Chen, Wei Chen Ho, Yue Ming Hsin, Jerry Tzou, Wen Hsien Huang, Chang Hong Shen, Jia Ming Shieh, Wen Kuan Yeh, Wen Ta Hsu, Sze Ching Liu

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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.

Original languageEnglish
Pages (from-to)6776-6782
Number of pages7
JournalJournal of Electronic Materials
Issue number11
StatePublished - 1 Nov 2020


  • AlGaN/GaN
  • enhancement mode
  • gate recess
  • p-GaN gate
  • second gate
  • short circuit


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