Photoadmittance in amorphous-silicon Schottky diodes

Abstract

The steady-state photoadmittance Y_ph(= G_ph + iωC_ph) of the depletion region in an amorphous-silicon Schottky diode has been measured for different frequencies, temperatures, illuminations and bias levels. A model for the temperature dependence of the space-charge photoadmittance in the depletion region is given; the loss contribution due to the transport of photo-generated holes across the depletion region is also considered. Experimental results for a Pt-a-Si: H diode are given and it is suggested that there is a one-to-one correspondence between the detail of G _ph as a function of temperature and the distribution of the gap-state density N(E) with energy. It is concluded that there is a peak in N(E) at 0·3–0·4 eV above E _v having an integrated density of 4 × 10^l5 cm⁻³.