[13p-PA9-1~25] 13.7 Compound and power electron devices and process technology

[13p-PA9-16] Effect of C or Fe doping to buffer layer on performance of AlGaN/GaN HEMT on GaN substrate

〇Takaaki Kondou¹, Hiroyuki Higashinakagawa¹, Naotaka Iwata¹ (1.Toyota Tech. Inst.)

Keywords:GaN substrate, AlGaN/GaN HEMT, buffer layer

Impurities are commonly doped to the buffer layer to achieve high resistivity for AlGaN/GaN HEMT on GaN substrate. However, the effect of doping on the performance of HEMT has not been clarified. The purpose of this paper is to clarify the effect of doping to GaN buffer layer on HEMT performances. HEMTs with C-doped and Fe-doped GaN buffer layers were fabricated respectively, and HEMT characteristics have been evaluated. The electron mobilities of 1900cm²/V·s were obtained for both of the HEMTs. The values are higher than that of a HEMT on Si substrate. The drain current of 480mA/mm was obtained for the C-doped HEMT with the threshold voltage of -1.5V. Then, the effect of doping was investigated by modulating the channel from the buffer layer using side gates. As a result, the channel of C-doped HEMT was modulated, whereas Fe-doped HEMT was not modulated. Consequently, the Fe-doped buffer layer HEMT is stable against external voltage changing.