Excitation of Trapped Electrons in SbSI

Abstract

The photoconductive and photo-diffusion effect of SbSI is investigated. The photocurrent and the short-circuit photovoltaic current depend not only on the photon energy but also on the polarization of the incident light. The photon energy showing the peak value of the photocurrent for the polarized light perpendicular to the c-axis is 0.05 eV higher than that for the polarized light parellel to the c-axis in both paraelectric and ferroelectric phases. The polarity reversal of the short-circuit photovoltaic current is observed.
From the results, it is suggested that there is the trap level at about 1.9 eV below the bottom of the conduction band and that the maximum photocurrent at around 1.9 eV is induced by the excitation of trapped electrons, while the photocurrent at a higher photon energy is induced by the generation of holes.