Growth of side facets in InP nanowires: First-principles-based approach

The initial growth processes on InP 1 1 ¯ 00 and InP 11 2 ¯ 0 surfaces are theoretically investigated to clarify temperature and pressure dependence of InP nanowire shape fabricated by selective area growth. Our Monte Carlo simulations in conjunction with density functional calculations for the growth processes with a realistic environment such as temperature and pressure reveal that there are several growth modes depending on the growth conditions. Due to lower growth rate on InP 11 2 ¯ 0 surface compared with InP 1 1 ¯ 00 surface, the nanowires grow along both vertical [0001] and lateral < 11 2 ¯ 0 > directions for low temperatures with high V/III ratio conditions. On the other hand, at high temperatures with low V/III ratio conditions, the nanowires grow along only vertical [0001] direction and form 1 1 ¯ 00 side facets due to lower surface energy on InP 1 1 ¯ 00 surface. The adsorption of P atoms on the surfaces are found to be crucial for the growth along the lateral direction of nanowires. The obtained results offer a possibility to predict and control nanowire shape by tuning growth conditions such as temperature and pressure.