INTERPRETING THE NONIDEAL REVERSE BIAS C-V CHARACTERISTICS AND IMPORTANCE OF THE DEPENDENCE OF SCHOTTKY-BARRIER HEIGHT ON APPLIED VOLTAGE

This work presents an attempt related to the charging behaviour of int erface states to the nonideal forward bias current-voltage (I-V) and t he reverse bias capacitance-voltage (C-V) characteristics of A1-nSi Sc hottky barrier diodes. The diode showed nonideal I-V behaviour with an ideality factor of 1.50 and was thought to have a metal-interface lay er-semiconductor configuration. Considering that the interface states localized at the interfacial layer-semiconductor interface are in equi librium with the semiconductor, the energy distribution of the interfa ce states was exactly determined from the forward bias I-V characteris tics by taking into account the bias dependence of the effective barri er height, Phi(e). The determination of the intercept voltage and inte rface state density was made by means of a simple interface charge mod el which has been developed in detail. The I-V characteristics were us ed for determining the voltage dependence of the barrier height. Altho ugh the change in barrier height with applied bias is small, it is imp ortant for exactly determining the shape of the interface state densit y distribution curve. At a frequency of 500 kHz, the nonlinear reverse bias C-2-V plot with the curvature concave downward has been only tho ught of to be due to the contribution of the capacitance of the interf ace state charges. It is concluded that the nonlinear nature of C-2-V plots in the frequency range 50-200 kHz has been caused by the interfa ce state charges as well as inversion layer and inversion layer charge s. It has been understood by means of the interface state charge model that the C-2-V plots cannot only be interpreted in terms of the contr ibution of the interface state charges to the device capacitance.