Fabrication of Recessed Structures for GaN HEMTs by a Simple Wet Etching Process

Taketomo Sato, Hokkaido University
Fumimasa Horikiri, Sciocs Company Limited
Noboru Fukuhara, SCIOCS Company Ltd.
Masachika Toguchi, Hokkaido University
Kazuki Miwa, Hokkaido University
Yoshinobu Narita, Sciocs Company Limited
Osamu Ichikawa, SCIOCS Company Ltd.
Ryota Isono, SCIOCS Company Ltd.
Takeshi Tanaka, SCIOCS Company Ltd.

Photoelectrochemical (PEC) etching is a promising technology for fabricating GaN devices with low damage. In the simple contactless PEC (CL–PEC) etching process that includes K2S2O8 in the electrolyte as an oxidizing agent, a sample is dipped into the electrolyte under UV irradiation. In this study, we applied CL–PEC to the gate-recess process of GaN HEMTs on an SiC substrate. The etching depth of the recess showed considerable reproducibility by the self-termination feature, and the residual AlGaN layer thickness was approximately 5 nm. The Schottky gate HEMTs with a recessed structure showed the normally off characteristics, and the Vth value was +0.4 V with a standard deviation of ±3.8 mV.

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