Growth control of GaAs nanowires using pulsed laser deposition with arsenicover-pressure

Abstract

Using pulsed laser ablation with arsenic over-pressure, the growth conditions for GaAs nanowireshave been systematically investigated. The single-crystal structure and geometry of thenanowires have been characterized for various growth conditions. Arsenic over-pressure withAs2 molecules was introduced into the system by thermal decomposition of polycrystallineGaAs to control the stoichiometry and shape of the nanowires during growth. GaAsnanowires exhibit a variety of geometries under varying arsenic over-pressures, which canbe understood by different growth processes via a vapor–liquid–solid mechanism. WithoutAs2 over-pressure, branched growth of GaAs with uncontrollable size and geometry wasobserved due to the decomposition of GaAs nanowires, producing metallic Ga which servesas catalysts for the branched growth of GaAs on the nanowire surfaces. Under optimalAs2 over-pressure, single-crystal GaAs nanowires with uniform diameter, small diameter distribution, lengthover 20 µm and thin surface oxide layer were obtained and used forI–V characterization.