Characteristics of InGaN with High In Concentrations Grown on ZnO at Low Temperatures

We have investigated the effect of substrate temperature on the structural properties of InGaN with high In concentrations grown on atomically flat ZnO substrates by pulsed laser deposition using an In0.65Ga0.35 alloy target. Although the InGaN film grown at 650 °C shows poor crystalline quality and has a rough surface, those grown at temperatures below 420 °C have surfaces with stepped and terraced structures. We found that the epitaxial growth of InGaN at low temperatures proceeds by the layer-by-layer mode, which is consistent with the atomically flat surfaces of InGaN. We also found that phase separation of InGaN is suppressed by reducing the growth temperature.