Role of high nitrogen flux in InAlN growth by plasma-assisted molecular beam epitaxy

We study the impact of increased active nitrogen flux (N-flux) on the indium content and structural properties of InAlN layers grown by plasma-assisted molecular beam epitaxy. It is shown that high N-flux can stabilize In-N bonds, so that In_0.18Al_0.82N is grown at 605 °C, which is the highest reported temperature so far for the composition lattice-matched (LM) to GaN. A diagram of InAlN indium content is shown as a function of growth temperature and N-flux. The InAlN layers grown using low and high N-flux had grainy surface morphology typical for N-rich conditions. Inhomogeneity in indium distribution on nanometer scale, i.e. typical honeycomb microstructure, is found for InAlN layers grown using both: low and high N-flux. An increase of average cell size is observed for LM-InAlN when the N-flux and growth temperature are increased.