[TuB4] High-Speed III-V Transistors

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[TuB4-05] High On/Off-Ratio Recessed-Gate E-Mode AlGaN/GaN MIS-HEMTs on Si with High Current Density for RF Applications

〇Tsung-Lin Lee¹, Po-Yen Huang², Haoran Wang¹, Yu-Hao Lin¹, Lung-Hsing Hsu³, Ming-Hsuan Kao³, Wen-Hsien Huang³, Chang-Hong Shen², Shawn S. H. Hsu¹, Roy K.-Y. Wong¹ (1. Inst. of Electronics Eng., National Tsing Hua Univ. (Taiwan), 2. College of Semiconductor Res., National Tsing Hua Univ. (Taiwan), 3. Taiwan Semiconductor Res. Inst. (Taiwan))

This paper presents high-performance enhancement-mode (E-mode) AlGaN/GaN MIS-HEMTs on Si substrates, designed for next-generation RF applications. To address the power management challenges of conventional depletion-mode devices, we employed a recessed-gate structure combined with an Al₂O₃/HfO₂ dielectric stack and n+ GaN regrown source/drain regions. In contrast to typical recessed-gate devices that often suffer from current degradation, the proposed E-mode MIS-HEMT delivers a high maximum drain current density (I_D,max) of 800 mA/mm, comparable to D-mode counterparts fabricated using the same baseline process. The device features superior gate control with a threshold voltage of +0.2 V and a high I_on/I_off ratio of ~ 10⁹. RF characterization demonstrates a cut-off frequency (f_T) of 30.4 GHz and a maximum oscillation frequency (f_max) of 57.1 GHz, confirming its suitability for sub-6 GHz wireless systems. These results validate the effectiveness of the recessed-gate technology in achieving both robust current drive and excellent switching capabilities for compact GaN RF front-ends.