On the effects of gate-recess etching in current-collapse of different cap layers grown AlGaN/GaN high-electron-mobility transistors

Influences of gate-recess etching with BCl₃ plasma in drain current (I_D) collapse were performed on different cap layers (i-GaN, n-GaN, and p-GaN) grown AlGaN/GaN high-electron-mobility transistors (HEMTs). Due to the decrease of dynamic-source-resistance by gate-recess, the increase of maximum drain current density and maximum extrinsic transconductance were observed in all cap layers grown AlGaN/GaN HEMTs. After gate-recess etching, about 14 and 17% of decrease in I_D collapse were observed on n-GaN and p-GaN cap layers HEMTs, respectively when compared to non-recessed HEMTs. However, increase (∼47%) of I_D collapse was observed in i-GaN cap layer HEMTs. The decrease of I_D collapse in doped GaN cap layer HEMTs is possibly due to the compensation of dopant related traps with plasma induced traps. The increase of I_D collapse in i-GaN cap layer HEMTs may be due to the incorporation of damage related traps by gate-recess etching. The decrease and increase of trapping effects were qualitatively confirmed by white-light illuminated I_DS-V_DS characteristics. An increase of gate leakage current in all recessed gate AlGaN/GaN HEMTs are due to the BCl₃ plasma induced damage.