DC characteristics of large gate periphery InAlN/GaN HEMT on sapphire substrate

A lattice-matched InAlN/GaN heterostructure was grown on sapphire substrate by using low-pressure metal organic chemical vapor deposition (MOCVD), and Hall effect measurements shown that the sheet charge density and electron mobility were 2.6×10¹³ cm^-3 and 1210cm²/V·s, respectively. Large gate periphery (2.5mm) high electron mobility transistors (HEMTs) with a gate length of 250nm and a source-drain spacing of 4 μ m were fabricated. The measurement results revealed that the drain current density was 248mA/mm at a gate-source voltage of -1V with a maximum extrinsic transconductance of 271.1mS/mm, and the extrapolated threshold voltage was -1.95V. The measurement of the gate leakage current indicated that the tunneling current is likely the primary mechanism.