On the impact of Gate field-plate length and barrier layer thickness on TDDB lifetime of GaN-on-Si MISHEMT devices for RF/5G/mm-Wave applications

A high gate-stack breakdown voltage is desired to enable the GaN-on-Si (MIS)HEMT device technology for upcoming RF/5G and mm-Wave applications. In this work, we show that the gate field-plate length (LGFP) has a considerable impact on the gate-stack TDDB lifetime for different gate-stack processing conditions and varying AlGaN barrier thickness. The TDDB lifetime is observed to increase with LGFP for devices suffering from high pre-stress gate-leakage, while it is observed to reduce with LGFP for devices with low gate-leakage and high RON dispersion. In devices with thinner AlGaN barrier, the higher RON dispersion results in further reduction of the TDDB lifetime. Additionally, the impact of L GFP on the TDDB lifetime is observed to reduce with thinner AlGaN barrier under similar processing conditions These results indicate a strong correlation between the gate-leakage and the barrier/cap interface properties, and their combined effect on the TDDB lifetime.