Schottky barrier heights of In0.5(AlxGa1−x)0.5P (0≤x≤1) lattice matched to GaAs

We report a systematic investigation; of the Schottky characteristics for the entire aluminum composition of In-0.5(AlxGa1-x)(0.5)P for the first time, using current-voltage measurements. The n-type Schottky barrier height phi(bn) has a minimum value of 0.85 eV at x = 0 and a maximum value of about 1.0 eV at the direct-indirect crossover point;(x = 0.55). With further increase of Al composition, phi(bn), decreases to 0.94 eV at x = 1.0. The improved Schottky barrier height provides In-0.5(AlxGa1-x)(0.5)P FETs, such as MESFETs and HEMTs, an additional advantage for power applications due to the reduced gate leakage current. We also found that both n-type and p-type Delta phi(b) = phi(b)(In-0.5(AlxGa1-x) P-0.5)-phi(b)(In0.5Ga0.5P) agree very well with their Delta E-c and Delta E-v, respectively, for the entire Al composition range.This general correlation can be most appropriately explained by Teroff's "intrinsic state pinning" model. (C) 1998 Elsevier Science Ltd.All rights reserved.