InAs self-organized quantum dashes grown on GaAs (211)B

We have grown InAs self-organized quantum dots and quantum dashes on GaAs (211)B substrates by molecular beam epitaxy. The growth temperature dependence of InAs nanostructures were studied by in situ reflection high-energy electron diffraction (RHEED) and ex situ atomic force microscopy. In the studied temperature range from 400 to 510 °C, the RHEED pattern changed from streaky to spotty after deposition of 6 ML of InAs, showing the formation of nanostructures. The quantum dots grown at lower growth temperatures (from 400 to 490 °C) showed bimodal dot size distribution. At higher growth temperatures, a drastic change from quantum dots to quantum dashes was observed. The quantum dashes have an asymmetric hutlike shape and align themselves along the [011̄] direction. The quantum dash width increases dramatically, whereas the average length and density increases slightly on further deposition of InAs.