Low Frequency Studies of Amorphous Silicon using a Dielectric Spectroscopic Method.

Abstract

Cr-metallised amorphous silicon samples have been studied as a function of temperature using a dielectric technique with probe frequencies in the range 10 mHz to 10 KHz. The data is presented in the form logC′, logC″ versus log frequency, where C′, C″ represent, respectively, the real and imaginary components of the complex capacitance. An accurate analysis of the data provides evidence of Schottky barrier-like behaviour in which the signature from the response of two deep centres is also observed. These represent the existence of two defects lying at energies of 0.61 and 0.74eV from a band edge. Additional information is shown in which the parallel barrier conductance is activated with an energy of 0.71eV. Similarities and differences due to different contact materials are discussed.