摘要
A comparative investigation on device characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) with SiN x , SiO x , and SiON passivation by using plasma enhanced chemical vapor deposition (PECVD) technique is conducted. The electrical performance of passivated GaN HEMTs are evaluated through DC current-voltage, pulsed current-voltage, and small-signal measurements. Obvious increases of 10.5% in drain current and of 8.6% in transconductance are observed for SiON passivated HEMT as compared with both the SiO x and SiN x passivated HEMTs. The SiO x passivated device is found to have lowest gate leakage current as well as off-state drain leakage current as compared to SiN x and SiON passivated devices. However, the pulsed I-V measurement shows a severe current collapse for SiO x passivated HEMT caused by the introducing of deep traps when compared with the SiN x and SiON passivated devices. Moreover, the small-signal measurement shows that the SiON passivated HEMT has a higher cut-off frequency due to the improvement in transconductance, which makes it a promising passivation layer for GaN based high power HEMT applications.