High uniformity of threshold voltage for GaAs/AlGaAs high electron mobility transistors grown on a Si substrate

Abstract

We report on a study of microscopic distribution of threshold voltage ( Vth) 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 Vth comparable to that for GaAs substrates is obtained, namely the standard deviation of threshold voltage (σ Vth) of 8.96 mV with the Vth of −101.3 mV for 150 points of the HEMT in a 1.95×1.9-mm2 area. From the evaluation of macroscopic (full wafer) and microscopic Vth distribution, high-density dislocations in the GaAs/Si are found not to affect the uniformity of Vth. This result indicates that HEMT/Si technology has a potential to lead the GaAs/Si to GaAs integrated circuit applications in which large-diameter wafers are beneficial.