Self-terminating contactless photo-electrochemical (CL-PEC) etching for fabricating highly uniform recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs)

Contactless photo-electrochemical (CL-PEC) etching was used to fabricate recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). Self-termination of etching was observed during CL-PEC etching on an AlGaN barrier layer whose residual thickness had a uniform value of 6 nm overall on the sa...

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Veröffentlicht in:Journal of applied physics 2021-07, Vol.130 (2)
Hauptverfasser: Toguchi, Masachika, Miwa, Kazuki, Horikiri, Fumimasa, Fukuhara, Noboru, Narita, Yoshinobu, Ichikawa, Osamu, Isono, Ryota, Tanaka, Takeshi, Sato, Taketomo
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Sprache:eng
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Zusammenfassung:Contactless photo-electrochemical (CL-PEC) etching was used to fabricate recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). Self-termination of etching was observed during CL-PEC etching on an AlGaN barrier layer whose residual thickness had a uniform value of 6 nm overall on the same chip. After tetramethylammonium hydroxide post-treatment, the root-mean-square roughness of the etched surface was around 0.4 nm, which had smoothness comparable to that of the unetched surface. Recessed-Schottky HEMTs showed a positive shift in Vth, the suppression of drain leakage currents, and an improvement in the subthreshold-slope value as compared with planar-gate HEMTs. By applying a metal–insulator–semiconductor (MIS)-gate structure, the gate and drain leakage currents were significantly reduced, leading to an increased input dynamic range. Furthermore, the standard deviations (σ) of the Vth of CL-PEC-etched recessed-Schottky HEMTs and recessed-MIS HEMTs were very small, 5.5 and 16.7 mV, respectively. These results showed that the CL-PEC etching process is promising for the fabrication of recessed-gate AlGaN/GaN HEMTs having excellent uniformity for normally-off device operations.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0051045