AlGaN/GaN high-electron-mobility transistors (HEMTs) were fabricated and the uniformity of dc properties were studied for the first time on 4-in diameter sapphire substrate. A quarter of 4-in diameter AlGaN/GaN epitaxial wafer was used for the uniformity studies of HEMTs. The observed average maximum drain current density, extrinsic transconductance and threshold voltage values for HEMTs were 515 mA/mm, 197 mS/mm, and -2.30 V with standard deviations 9.34%, 4.82%, and 6.52%, respectively. The uniformity of Hall mobility across the 4-in wafer was 1322 cm2/Vs with a standard deviation of 4.27%. The uniformity of sheet resistance across 4-in diameter wafer, measured using Hall Effect was 575 Ω/sq. with a standard deviation 9.01%. The uniformity of HEMTs dc properties are in good correlation with the electrical characteristics of AlGaN/GaN heterostructures, which was obtained from the Hall Effect and capacitance-voltage (C-V) measurements.
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