The capacitance of rf sputtered hydrogenated amorphous silicon, Schottky barrier diodes

A generalized interpretation of the capacitance/conductance behavior in a hydrogenated amorphous silicon Schottky barrier is introduced. This approach takes into account the influence of voltage, temperature, frequency, and light intensity on the capacitance and conductance characteristics of a Schottky barrier junction and on a complete device. From the various different considered cases it is possible to obtain information on the barrier profile, depletion width of the barrier, and density of states in the gap. The model proposed provides a method of obtaining the ‘‘active’’ charge that effectively determines the capacitance in the barrier. Comparison of theoretical predictions based on the model with experimental data from capacitance and conductance measurements of reactively sputtered, hydrogenated a-Si:H-metal Schottky barrier structures as a function of temperature voltage, frequency, and illumination shows good agreement.