Near-ideal Schottky contact on quaternary AlInGaN epilayer lattice-matched with GaN.

Pd/Ti/Au and Ni/Au Schottky barrier diodes (SBDs) were demonstrated on quaternary AlInGaN. Current–voltage properties indicated that near-ideal and high-performance SBDs had been realized with ideality factor of 1.05, 1.07 and barrier height of 1.32, 0.98 eV for Pd and Ni SBDs, respectively. Capacitance–voltage measurement revealed that the high-density two-dimensional electron gas (2DEG) located at the AlInGaN/GaN interface. Ruling out the possible contribution from piezoelectric polarization and conduction band offset, we believe that the formation of 2DEG is due to the existence of large spontaneous polarization in AlInGaN layer, which experimentally verifies the feasible application of quaternary AlInGaN in the high-electron-mobility transistor. [ABSTRACT FROM AUTHOR]