Some effects of (NH4)(2)S-x treatment of n-GaAs surface on electrical characteristics of metal-SiO2-GaAs structures

The measurements of the frequency dependence of MIS capacitance and conduct ance have been performed for the Au/Pd/Ti-SiO2-GaAs structures. The (100) o riented n-GaAs wafers with and without (NH4)(2)S-x surface treatments have been used. The anomalous frequency dispersion of MIS capacitance at positiv e biases and broad maximum of MIS conductance G(m)/omega versus frequency w ith position dependent on gate voltage have been observed for both types of investigated structures. For (NH4)(2)S-x-treated samples the additional pe ak on G(m)/omega versus frequency curves with position independent on gate voltage, resulting from contribution of deep traps in semiconductor as well as dispersion of MIS capacitance at negative biases have been registered. The creation of negative charge at insulator-GaAs interface during sulfur t reating of GaAs surface is discussed as a factor favourable to manifestatio n of deep trap contribution to measured MIS admittance. (C) 2000 Elsevier S cience Ltd. All rights reserved.