Understanding Sn-seeded InSb nanowire growth

Abstract: III-Sb semiconductor nanowires have drawn a lot of attention because of their many promising applications, such as thermoelectric generation, low power high efficient electronics and quantum transport. Gold as a catalyst seed particle has been dominating for many years assisting nanowires growth. However, gold is incompatible with silicon-based electronics, which is dominating today. Therefore, finding metals alternative to gold as catalyst seed particles for III–V semiconductor nanowire growth is necessary. Sn was chosen as a promising seed particle for InSb nanowires growth. The most commonly used bottom - up method is the Vapor - Liquid - Solid (VLS) mechanism. This project consisted of both experimental and theoretical components, with the aim to develop the growth of InSb semiconductor nanowires using Sn droplets and Metal Organic Chemical Vapour Deposition (MOCVD). The composition of the Sn seeded InSb nanowires (including the seed particle) were determined by X-ray energy dispersive spectroscopy (XEDS). The morphology was characterized by scanning electron microscopy (SEM). Sn-seeded InSb nanowires growth was also discussed from a thermodynamic viewpoint using the phase diagram. The optimized growth temperature was found to be 420C. The growth rate is low. Due to sample edge effects, the morphology of the nanowires (excluding the seed particle) is different between center and edge of the sample. The resulting InSb nanowires are much thicker (450 nm) and shorter (450 nm) compared to gold-seeded InSb nanowires. The nucleation and polarity of Sn-seeded InSb nanowires are more affected by V/III ratio than temperature. Particle size is strongly influenced by TMIn flow. The Sb amount is a key factor to control the morphology of InSb nanowires. We conclude that Sn-seeded InSb nanowires growth results in self-seeded (In) seeded InSb nanowires growth. The reasons are: 1). The seed particle size increases much during nanowires growth, from about 150 nm to 403 nm; 2). There is no significant effect on particle size with smaller seed particles growth; 3). XEDS measurements show that no Sn is detected. Mass transport modeling fits the experimental data of TMIn series much better than TMSb series. Further experiments on InSb nanowires growth without Sn seed particles verified that Sn-seed particles help nucleation and affect the InSb NWs growth.