Epitaxial synthesis, band offset, and photoelectrochemical properties of cubic Ga2S3 thin films on GaAs (111) substrates

Abstract

Uniform and crack-free cubic Ga2S3 thin films have been epitaxially synthesized on n-GaAs (111) substrates by sulfurization. Atomic-force microscopy revealed that the Ga2S3 surface is dominated by nanoparticles of smaller than 50 nm in diameter. The nanoparticles, clustered into regular triangle structures that hierarchically packaged on GaAs, significantly reduced the reflectance of GaAs. Low-temperature photoluminescence revealed typical acceptor-like defects while X-ray photoemission spectroscopy revealed type-I heterojunctionwith a valence-band offset of 0.6 eVfor theGa2S3/GaAs heterostructure. Photoelectrochemical properties of the Ga2S3/n-GaAs (111) heterojunction are studied and compared with those of bare n-GaAs (111) substrate in a typical three-electrode setup.