Performance Enhancement of AlGaN/GaN HEMT via Trap-State Improvement Using O2 Plasma Treatment

• Published in: IEEE transactions on electron devices Vol. 70; no. 6; pp. 2988 - 2993
• Main Authors: Amir, Walid, Shin, Ju-Won, Shin, Ki-Yong, Chakraborty, Surajit, Cho, Chu-Young, Kim, Jae-Moo, Lee, Sang-Tae, Hoshi, Takuya, Tsutsumi, Takuya, Sugiyama, Hiroki, Matsuzaki, Hideaki, Kim, Dae-Hyun, Kim, Tae-Woo
• Format: Journal Article
• Language: English
• Published: New York The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 01.06.2023
• Subjects: Aluminum gallium nitrides; Barrier layers; Bulk density; Electron mobility; Gallium nitrides; LF noise; Oxygen ions; Oxygen plasma; Plasma; Short pulses; Transconductance; Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3268626

Herein, we present a detailed analysis of the effects of O2 plasma treatment on the AlGaN barrier volume trap states in an Al0.45Ga0.45N/GaN high-electron mobility transistor. Compared to that of the as-grown sample, the single short-pulse [Formula Omitted]–[Formula Omitted] characterization of the plasma-treated sample exhibited lower charge trapping inside the AlGaN barrier. The 1/[Formula Omitted] low-frequency noise characterization revealed a significant reduction of approximately 67% in the volume trap density of the AlGaN barrier layer after O2 plasma treatment. This was achieved by the formation of Al–O and Ga–O bonds via the penetration of oxygen ions into the AlGaN bulk, which resulted in reduced trap state density in the AlGaN barrier. In addition, the Schottky characteristics were improved notably. Consequently, the O2 plasma-treated sample did not display current collapse and showed steady drain current output under the reverse-sweep drain-stress bias conditions. Furthermore, the plasma treatment significantly reduced the RF transconductance ([Formula Omitted]) collapse in the as-grown sample, and significantly increased the [Formula Omitted] of the plasma-treated sample from 65/70 to 120/230 GHz for [Formula Omitted] = 80 nm devices, respectively. Last, the O2 plasma-treated sample showed substantial improvements in [Formula Omitted], power added efficiency (PAE), and linear gain from 1.25 W/mm, 20%, and 15 dB to 2.4 W/mm, 50%, and 19 dB, respectively.