Spectroscopic photo I-V diagnostics of nitride-based high electron mobility transistor structures on Si wafers

A simple and novel spectroscopic photo I–V method of diagnosing the homogeneity of electrically-active defect distribution in the large area AlGaN/GaN HEMT (high electron mobility transistor) epi-structure grown on 6-inch silicon wafers is reported. It is of utmost importance to produce the HEMT epi-structure electrically homogeneous across the wafer if devices with uniform electrical characteristics are to be constructed. AlGaN/GaN HEMT epi structures were grown on a silicon substrate via metal–organic chemical vapour deposition. An array of circular semi-transparent Ni Schottky contacts was prepared on top of the diced AlGaN/GaN HEMT structure substrates, which were selected from different locations of the 6-inch wafer. The information of the electrical homogeneity across the wafer was elucidated from the spectral dependences of the I–V characteristics collected from different locations of the AlGaN/GaN HEMT wafer. It is successfully demonstrated that the proposed spectroscopic photo I–V measurement technique can be employed to diagnose electrical homogeneity of the electrically-active defect distribution in the AlGaN/GaN HEMT epi structure constructed on Si with minimum sample preparation steps.