GaAsSe Ternary Alloy Nanowires for Enhanced Photoconductivity

Abstract

Alloyed semiconductor nanowires (NWs) are of great interest for next-generation integrated optoelectronic nanodevices owing to their tunable band gap and emission wavelength. In this study, we synthesized the GaAsSe ternary alloy nanowires (NWs) with various compositions between GaAs and Ga2Se3 using chemical vapor transport method. The band gap was continuously tuned in the range of 1.5-2.1 eV because of the completely miscible solid solution at all compositions. The alloy NWs (including Ga2Se3) consisted of a cubic phase with the [011] growth direction, in contrast with the GaAs NWs grown along the [111] direction. In particular, the GaAs1-xSex (x = 0.3) alloy NWs were grown from Ga-rich Au nanoparticles such as cubic-phase AuGa2 and had a defect-free single-crystalline nature. X-ray photoelectron spectroscopy analysis reveals much less surface oxide layers for x = 0.3, suggesting that Se incorporation at this composition effectively diminishes the surface defects. We fabricated photodetectors using the individual NW, showing that the photocurrent decreases with the increasing Se composition. The alloy composition significantly diminished the dark current and thus greatly enhanced the photosensitivity for x = 0.3.