Characteristics of MIS capacitors using Ta2O5 films deposited on ZnO/p-Si

Abstract

The electronic availability of ZnO thin film as a semiconducting material for MIS structure was investigated by depositing a dielectric Ta2O5 thin layer. A ZnO (100 mn) thin film was deposited on p-Si by rf magnetron sputtering. High frequency (1 MHz) capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of the deposited Ta2O5 films were measured. The values of flat-band (V-fb) voltages are found to be -1.6 V and the negative flat-band voltage shift with respect to the ideal MIS capacitor indicates the existence of positive charge trapping in the plasma grown Ta2O5 films. The fixed oxide charge density (Q(f)/q) is found to be 2.48 X 10(11) cm(-2) while the interface trap charge density (D-it) at mid-gap, calculated using Hill's method from the G-V curve, is found to be 1.22 X 10(12) cm(-2) eV(-1). (C) 2002 Elsevier Science B.V. All rights reserved.