Electrical characteristics of metal-insulator-semiconductor Schottky diodes using a photowashing treatment in AlzGa1-xAs/InGaAs (X=0.75) pseudimorphic high electron mobility transistors

Abstract

MIS Schottky diodes on Al0.75Ga0.25As/In0.2Ga0.8As PHEMTs were produced using both photowashing and H2O2 treatments. The Schottky contact on the GaAs layer with photowashing and H2O2 treatments showed enhancements of the SBH of about 0.11 and 0.05 eV, respectively. However, on the undoped AlGaAs layer, no further improvement in SBH was observed. After the photowashing treatment, the Ga oxide (Ga2O3) was dominantly created. In the mean time, two types of As oxide (As2O3,As5O2) were mainly produced by the H2O2 treatment, which are distributed uniformly on the GaAs surface. The thickness of the oxide layer formed by both treatments was nearly the same. Applying a representative model, formation of Ga oxide after the photowashing treatment effectively enhanced the SBH.