Synthesis of indium oxide nanorods on indium phosphide substrate using plasma immersion ion implantation

We report the preparation of indium oxide (In2O3) nanorods on indium phosphide (InP) substrate by plasma immersion ion implantation (PIII). The InP substrate was first treated with PIII of acetylene (C2H2) ions, then followed by coating the surface with a 40 nm thick gold film. After rapid thermal anneal (RTA) at 750 °C for 15 s, In2O3 nanorods were found on InP surface. The In2O3 nanorods with diameters of 50–200 nm were examined by Raman spectroscopy, scanning electron microscopy (SEM) and cathodoluminescence (CL). Nanoparticles of gold were found at the tip of the nanorods, suggesting that a vapour–liquid–solid (VLS) mechanism was involved. However, the fact that other species such as nitrogen, argon or oxygen would not lead to the formation of In2O3 nanorods also suggests that the carbon liberated from C2H2 plays an important role as a catalyst. Carbon has previously been reported to be a reduction agent for the formation of group III sub-oxides. Such sub-oxides provide the vapour source for the growth of nano-materials through further oxidation.