Poly-Si gate electrodes for AlGaN/GaN HEMT with high reliability and low gate leakage current

Abstract

AlGaN/GaN HEMT with a BF2-implanted polycrystalline Si gate has been characterized through comparison to TiN gate electrodes. Positive threshold voltage (Vth) shift was observed with the addition of F ions, which in turn degraded the effective electron mobility (μeff) by diffusion into the AlGaN/GaN interface and GaN layer. A large reduction in gate leakage current (Jg) was achieved and the property was maintained even after strong reverse-bias stressing. No additional degradation in μeff was observed, suggesting the formation of a stable poly-Si/AlGaN interface. Therefore, poly-Si gate electrodes have advantages in reducing the Jg and robustness against reverse-bias stressing.