Effects of nitrogen plasma irradiation during the growth process after buffer layer growth on the characteristics of hexagonal InN films grown on Si (1 1 1) by electron-cyclotron resonance plasma-assisted molecular-beam epitaxy

摘要

We report the effects of nitrogen (N) plasma irradiation during the growth process after buffer layer growth on the characteristics of hexagonal (α) InN films grown on Si(1 1 1) substrates by electron-cyclotron resonance plasma-assisted molecular-beam epitaxy. (0001)-oriented single-crystalline α-InN films were dominantly grown independently of N plasma irradiation during the process. However, the crystalline qualities were greatly improved by irradiation in the high-growth-temperature region, effectively suppressing re-evaporation of N atoms from InN. Moreover, the n-type carrier concentrations of the N plasma-irradiated samples decreased to about 10~(18)-10~(19)cm~(-3), one to two orders lower than those without irradiation. A strong infra-red PL emission of 0.75eV was observed on the whole surface between 4 and 300 K, only from samples grown under weak N plasma conditions and irradiated by N plasma during the process. The origin of the residual donor impurities was determined to be related to N vacancy.