Liquid-solid and vapor-solid distributions of vapor-liquid-solid III-V ternary nanowires
В. Г. Дубровский
Abstract
III-V ternary nanowires and nanowire heterostructures offer almost unlimited possibilities for the band-gap design and can be integrated with Si electronic platform. Most of such nanowires are grown by the vapor-liquid-solid method. The presence of a catalyst droplet, which is a quaternary liquid alloy for Au-catalyzed III-V ternary nanowires, significantly complicates the analysis of the nanowire composition versus the vapor and liquid compositions. Herein, we develop a growth theory of III-V ternary nanowires and obtain the stationary liquid-solid distribution in a rather general form. It is shown that the liquid-solid distribution is close to equilibrium, or nucleation limited, for nanowires based on group III intermix, and becomes kinetically controlled for nanowires based on group V intermix. These principally different behaviors are due to extremely low concentrations of highly volatile group V elements in a droplet, leading to group V limited liquid-solid growth. We also consider the vapor-solid distributions of III-V ternary nanowires and demonstrate that they are controlled by the material influxes into the droplet, and almost independent of the liquid composition in many cases, at least for ternaries based on group III intermix. The examples of the liquid-solid and vapor-solid distributions are given for different material systems including Au-catalyzed InGaAs and AlGaAs nanowires, and self-catalyzed InPAs, GaSbAs, and AlSbAs nanowires, which fit very well the available experimental data.