Comparison of Si doping effect on GaN nanowires and films synthesized by metal-organic chemical vapor deposition.

We investigated Si doping effect on GaN nanowires and GaN films grown by metal-organic chemical vapor deposition (MOCVD). Si as n-type dopant is incorporated to GaN nanowires and GaN films controlled by SiH4 flow rate (0, 1, 5, 8, and 10 sccm). The charge concentration and mobility of GaN films increased and decreased, respectively, as increasing the SiH4 flow rate, whereas those for GaN nanowires were not influenced by the SiH4 flow rate. Significant vacancies and impurities resulted in the intense yellow band in GaN nanowires as compared with GaN films, which leads to the large device-to-device variation and negligible dependence of Si doping and the SiH4 flux rate on the electrical properties of GaN nanowires.