Electrical characteristics of metal-insulator-semiconductor Schottky diodes using a photowashing treatment in Al_xGa_(1-x)As/InGaAs (X = 0.75) pseudomorphic high electron mobility transistors

摘要

Metal―insulator―semiconductor (MIS) Schottky diodes on Al_(0.75)Ga_(0.25)As/In_(0.2)Ga_(0.8)As pseudomorphic high electron mobility transistors were produced using both photowashing and H_2O_2 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 H_2O_2 treatment, respectively. After the photowashing treatment, the Ga oxide (Ga_2O_3) was dominantly created. In the meanwhile, two types of As oxide (As_2O_3 ,As_5O_2) were mainly produced by the H_2O_2 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.