First Demonstration of an N-Polar InAlGaN/GaN HEMT

In this letter, we report the first N-polar InAlGaN quaternary back barrier high-electron-mobility transistor (HEMT). The epitaxial device heterostructure was grown by metal organic chemical vapor deposition (MOCVD). Hall measurements of the heterostructure showed a two-dimensional electron gas (2DEG) density of 2.85x10(13) cm(-2) and a mobility of 1048 cm (2)s(-1)V(-1) . Transfer length method measurements showed a remarkably low sheet resistance of 179 Omega/square in the source-drain direction. A HEMT with a gate length of 0.6 mu m and source-drain spacing of 3.1 mu m showed a peak transconductance of 212 mS/mm and a high peak DC drain current of 1.92 A/mm. Small signal measurements of an equivalent HEMT yielded a current-gain cut-off frequency ( f(T)) and power-gain cut-off frequency (f(max)) of 18 GHz and 28 GHz, respectively, at peak f(max) bias conditions (VGS = -9 V and VDS = 5 V).