Growth and luminescence characterization of dilute InPN alloys grown by molecular beam epitaxy

The authors have investigated the growth and luminescence properties of InPN alloys grown by solid-source molecular-beam epitaxy (MBE). The N composition increases with decreasing growth rate, P-2/In flux ratio, and growth temperature. In this work, the highest N composition obtained is 0.56% for the InPN sample. The appropriate growth temperature is around 400 degrees C. However, the growth-temperature window of the InPN alloys having a smooth surface is very narrow. In order to obtain photoluminescence (PL) emission from the InPN samples grown by solid-source MBE, InPN alloys must be grown under the condition of lower-plasma power since the grown-in point defects induced by N plasma are reduced. Thermal treatment is effective to improve the luminescence efficiency of InPN alloys, and the appropriate annealing temperature is around 700 degrees C. However, the S-shape behavior is observed only for the annealed InPN samples by atomic rearrangements during thermal treatment, which is attributed to the weaker bond strength of In-N than that of In-P. In addition, the PL peak energy corresponding to the near-band edge emission redshifts with increasing annealing temperature. These results indicate that the luminescence properties of InPN alloys are unique in contrast to other dilute nitrides such as GaAsN and GaPN alloys.