Phase Separation and Ordering in InGaN alloys

Abstract

ABSTRACTWe investigated phase separation and long-range atomic ordering in InGaN alloys grown on (11–20) sapphire substrates by molecular beam epitaxy (MBE). Compositional inhomogeneities were found in films grown at substrate temperatures ranging from 650 – 675°C when the indium content was larger than 20%. Upon annealing to 725°C, these films underwent phase separation, similar to films grown at 725° C.These InGaN films also showed the evidence of long-range atomic ordering, with the order parameter being a function of film composition and the growth parameters. A competition between ordering and phase separation has been observed, suggesting that the driving force for both phenomena is lattice strain in the alloy.