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

Metal-insulator-semiconductor (MIS) Schottky diodes on Al0.75Ga0.25As/In0.2Ga0.8As pseudomorphic high electron mobility transistors were produced using both photowashing and H2O2 treatments. The Schottky contact on a GaAs layer showed enhancement of the Schottky barrier height of 0.11 eV for the photowashing and 0.05 eV for the H2O2 treatment, respectively. After the photowashing treatment, the Ga oxide (Ga2O3) was dominantly created. In the meanwhile, two types of As oxide (As2O3, As5O2) were mainly produced by the H2O2 treatment, which were distributed uniformly over the GaAs surface. At the same oxide thickness, the formation of the Ga oxide after the photowashing treatment is more effective in enhancement of the Schottky barrier height. This is due to the fact that the Ga oxide was more favorable in the creation of a fixed interface state density, which is known as an origin for increase of the barrier height, compared to the As oxide in the GaAs MIS Schottky diode. (C) 2003 American Vacuum Society.