AlGaN/GaN-HEMTs on SiC with SiN Passivation Film Grown by Thermal CVD(Session9B: GaN and SiC Device Process Technology)

概要

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Current collapse phenomenon is a well known obstacle in the AlGaN/GaN high electron mobility transistors (HEMTs). In order to improve the surface stability of HEMTs, we have investigated the SiN passivation film deposited by thermal chemical vapor deposition (T-CVD), and we found that it improves both gate leakage current and current collapse phenomenon. Moreover, we compared the T-CVD and plasma enhanced chemical vapor deposition (PE-CVD) passivation films, on high electric field DC characteristics and on RF characteristics by the on-wafer load-pull power measurement. We found out that T-CVD SiN passivation film improves three-terminal off-state breakdown voltage (BV_<ds-off>) by 30% because of the reduction of gate leakage current. It also improved drain efficiency (η_d) in the output power characteristics by load-pull measurement, which indicates the decrease of the current collapse phenomenon. Also we fabricated a multi-fingered 50 W-class AlGaN/GaN-HEMT with T-CVD SiN passivation film and achieved 61.2% of high drain efficiency at frequency of 2.14GHz, which was 3 points higher than those with PE-CVD SiN passivation film.
社団法人電子情報通信学会の論文
2008-07-02