Drastic reduction of gate leakage in InAlAs/InGaAs HEMT's using a pseudomorphic InAlAs hole barrier layer

Insertion of a thin pseudomorphic InAlAg hole barrier layer having high Al content into the spacer of an InAlAs/InGaAs HEMT increases the valence band discontinuity and decreases the excess gate leakage current. Photocurrent and DC measurements help determine the efficiency of the hole barrier while Hall and RF measurements help determine the influence of hole barrier on transport characteristics. Experimental results show that impact ionization in the InGaAs channel is responsible for the excess gate leakage current.