Molecular beam and pulsed laser deposition of ZnS:Cr for intermediate band solar cells

Abstract

We have investigated the structural and optical properties of Cr-doped ZnS (ZnS:Cr) thin films (0–7.5 at.% Cr) for use in intermediate band solar cells. The films were grown on Si(100) in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) equipments. Introducing Cr into ZnS resulted in Cr related subbandgap absorption, but also reduced the grain size. The sub-bandgap absorption increased with increasing Cr content, and with increasing growth temperature, but did not depend on the growth method. In contrast, the crystallinity depended strongly on the growth method, and smoother and highly textured films were obtained by PLD. The data indicate that stacking faults are present in all films.