The influence of lightly doped p-GaN cap layer on p-GaN/AlGaN/GaN HEMT

In this paper, the influence of a lightly doped p-GaN (p(-)-GaN) cap layer on p-GaN/AlGaN/GaN high electron mobility transistors (HEMTs) (LDP-HEMTs) was investigated. No difference in output or off-state breakdown characteristics was observed, but there was a negative shift in threshold voltage (V (TH)). The gate leakage (V (GS) = 7 V) dropped by three orders of magnitude, and the gate forward breakdown voltage and continuous operating voltage increased by 6.5 V and 2.5 V, respectively. It is worth noting that the gate characteristics are significantly optimized, which is ascribed to the employment of the p(-)-GaN cap layer. The simulations illustrate that the electric field is dispersed, and the electric peak is alleviated by the p(-)-GaN cap layer, thus suppressing the impact ionization and carrier injection in the high electric field. Furthermore, there is a negligible effect on the temperature reliability of V (TH) based on the temperature-dependent characteristics in LDP-HEMTs. However, the temperature stability of the gate current (V (GS) = 7 V) will worsen in LDP-HEMTs due to the difference in the conduction mechanism, compared with conventional p-GaN HEMTs.

Automated summary

This paper investigates the influence of a lightly doped p-GaN cap layer on p-GaN/AlGaN/GaN high electron mobility transistors (HEMTs). The results show that the p(-)-GaN cap layer optimizes the gate characteristics, significantly reduces the gate leakage voltage, and increases the gate forward breakdown voltage and continuous operating voltage. Furthermore, simulation results demonstrate that the p(-)-GaN cap layer disperses the electric field and alleviates the electric peak, thereby suppressing impact ionization and carrier injection.