HIGH UNIFORMITY OF THRESHOLD VOLTAGE FOR GAAS ALGAAS HIGH-ELECTRON-MOBILITY TRANSISTORS GROWN ON A SI SUBSTRATE/

We report on a study of microscopic distribution of threshold voltage (V(th)) for GaAs/AlGaAs high electron mobility transistors (HEMTs) on a Si substrate grown by metal-organic chemical vapor deposition (MOCVD ). Using selective dry etching, the superior microscopic distribution of V(th) comparable to that for GaAs substrates is obtained, namely th e standard deviation of threshold voltage (sigma V(th)) of 8.96 mV wit h the V(th) of -101.3 mV for 150 points of the HEMT in a 1.95 x 1.9-mm 2 area. From the evaluation of macroscopic (full wafer) and microscopi c V(th) distribution, high-density dislocations in the GaAs/Si are fou nd not to affect the uniformity of V(th). This result indicates that H EMT/Si technology has a potential to lead the GaAs/Si to GaAs integrat ed circuit applications in which large-diameter wafers are beneficial.