Photovoltaic properties of indium selenide thin films prepared by van der Waals epitaxy

Abstract

Indium selenide thin films have been grown on gallium selenide single crystal substrates by van der Waals epitaxy. Low energy electron diffraction patterns show that the film grows with the substrate orientation and its valence band photoemission spectrum exhibits the same structure as single crystals. The film absorption edge has been studied through the photovoltaic spectra as a function of temperature. The optical gap value and its temperature dependence are those measured in bulk indium selenide, but exciton peaks are not observed even at low temperature, which reveals a large defect concentration.