Plasma-assisted molecular beam epitaxy growth diagram of InGaN on (0001)GaN for the optimized synthesis of InGaN compositional grades

A PAMBE (plasma-assisted molecular beam epitaxy) growth diagram of InGaN is established for the metal-face (0001) orientation at 575 degrees C. This growth diagram allows identifying different growth regimes during the epitaxy of InGaN, namely the N-rich, the Ga-rich, the intermediate In-rich, and the In-accumulation regimes. InGaN compositional grades are then grown by ramping the Ga and In fluxes in parallel to remain in either the intermediate In-rich or the N-rich regime. The two samples exhibit distinct structural characteristics, surface morphologies, and optical properties. The growth diagram proves to be a useful tool in controlling the metal fluxes and thereby the stoichiometry conditions on the surface during the growth of compositionally graded layers.