Comparison of Al[sub 0.32]Ga[sub 0.68]N∕GaN Heterostructure Field-Effect Transistors with Different Channel Thicknesses

heterostructure field-effect transistors (HFETs) grown by low-pressure metallorganic chemical vapor deposition are successfully fabricated. A Mg-doped insulating layer is inserted to suppress the leakage current, improve the breakdown voltages, and yield excellent pinch-off characteristics. Moreover, HFETs with different channel thicknesses of 1200, 1500, and are investigated. Experimental results show that an HFET with a thick channel layer has the highest electron mobility, electron concentration, drain current, and extrinsic transconductance.