Evolution of phase separation in In-rich InGaN alloys

Evolution of phase separation in $InxGa1−xN$ alloys $(x∼0.65)$ grown on AlN/sapphire templates by metal organic chemical vapor deposition has been probed. It was found that growth rate, $GR$⁠, is a key parameter and must be high enough $(>0.5μm/h)$ in order to grow homogeneous and single phase InGaN alloys. Our results implied that conditions far from thermodynamic equilibrium are needed to suppress phase separation. Both structural and electrical properties were found to improve significantly with increasing $GR$⁠. The improvement in material quality is attributed to the suppression of phase separation with higher $GR$⁠. The maximum thickness of the single phase epilayer $tmax$ (i.e., maximum thickness that can be grown without phase separation) was determined via in situ interference pattern monitoring and found to be a function of $GR$⁠. As $GR$ increases, $tmax$ also increases. The maximum value of $tmax$ for $In0.65Ga0.35N$ alloy was found to be $∼1.1μm$ at $GR>1.8μm/h$⁠.