Shape transition of InAs quantum dots by growth at high temperature

The shape of InAs quantum dots grown on GaAs substrates by molecular beam epitaxy is investigated at various growth temperatures. A dot with a new shape surrounded by {110} facets and having a high aspect ratio appears at temperatures over 510 °C. This dot is transformed from a pyramid shape (low aspect ratio) when its volume exceeds a critical value by raising the growth temperature. The shape transition indicates that the high-aspect-ratio dot is energetically favorable at a large volume. A narrow energy width of photoluminescence, 35 meV at room temperature, is obtained by the growth of the high-aspect-ratio dots, which have a fairly good size uniformity of less than 4% deviation.