Molecular beam epitaxy of InAlN alloys in the whole compositional range

Abstract

The fabrication of high-quality InxAl1-xN alloys over the whole composition is very challenging. Controlling the In/(In + Al) beam flux ratio and the growth temperature, this paper reports the fabrication of single crystalline InxAl1-xN alloys over the whole In composition by radio-frequency plasma-assisted molecular beam epitaxy. A comprehensive systematic study on the structural and vibrational properties of the InxAl1-xN alloys for the whole In composition has been carried out experimentally by Raman spectroscopy and theoretically by the forced vibrational method. The InxAl1-xN alloys show broad Raman peaks in the intermediate range of In composition. The appearance of Raman inactive B1 (High) mode has been confirmed by the experimental and theoretical results. The B1 (High) and A1 (LO) modes show one-mode behavior, whereas the E2 (High) mode shows the two-mode behavior in the whole In composition range. The observed Raman modes from the grown InxAl1-xN alloys well match with the calculated phonon modes of the InxAl1-xN alloys. These results provide an in-depth understanding of the growth of whole compositional InxAl1-xN alloys and the fabrication of optoelectronic devices using these promising materials.