Effect of selective hydrogen pretreatment on the characteristics of AlGaAs/InGaAs p-HEMTs

Abstract

The DC, the RF, and the low-frequency noise characteristics of selective H-2-pretreated Al0.24Ga0.76As/In0.2Ga0.8As double heterostructure were investigated. The hydrogen-pretreated p-HEMT gate was formed by treating an AlGaAs Schottky barrier layer with different hydrogen plasma powers and by proper thermal annealing prior to gate metallization. Strong dependences of the threshold voltage and the low-frequency noise characteristics on the RF-power of the hydrogen plasma and on the annealing temperature were observed. The atomic hydrogen generated under different RF powers passivated the donor ions and damaged the surface. However, a proper subsequent RTA partially reactivated donor ions while curing the surface, resulting in a lower gate leakage current and low-frequency noise, as well as a large threshold shift (0.72 V for 100 W) due to residual passivated donors. These results indicate the potential of selective hydrogen treatment (SHT) for use in fabricating enhancement/depletion (E/D) mode p-HEMTs.