Electron-beam Irradiation during Schottky Gate
Metallization of GaAs FET
Tomoyuki Ohshima, Hirotomo Ozawa, Hironobu Moriguchi, Ryoji Shigemasa, Masanori Tsunotani. Tamotsu Kimura
III-V Devices Department, Components Division, Oki Electric
550-1 Higashiasakawa, Hachioji, Tokyo 193-8500, Japan
The electron-beam irradiation damage during Schottky gate metallization of GaAs FET has been investigated. It has been found that the damage introduced within GaAs during the electron-beam deposition strongly related to the electron-beam irradiation dose, which depended on the evaporated metal species. For the Mo Schottky gate HEMT. the threshold voltage shifts towards the positive direction after the forward gate current test due to a large concentration of deep-traps under the gate induced by the electron-beam irradiation. In order to suppress such an instability of the device characteristics, it is effective to insert a Ti layer with a small electron-beam irradiation dose during the deposition.