Substrate dependence on the growth of defective-wurtzite Al₂S₃ thin films using pulsed laser deposition

Abstract

Wurtzite ferroelectrics such as AlScN have been extensively studied in recent years because they promise the compatibility to semiconductor technologies. These materials have higher remanent polarization than that of perovskite ferroelectrics, however its coercive field is very large comparing to them. Defective-wurtzite Al₂S₃ has been expected to have ferroelectricity with relatively low switching barrier comparing to AlN by a theoretical calculation. To evaluate experimentally its ferroelectric properties in the future, the deposition and growth of Al₂S₃ thin films and its dependences of various substrates were studied using pulsed laser deposition. It was demonstrated that Al₂S₃ can be grown epitaxially on α-Al₂O₃(0001) and SrTiO₃(111) while Pt(111)/α-Al₂O₃(0001) is not applicable to the growth.