Formation of InAs quantum dots on GaAs(100) by chemical beam epitaxy

We report the formation by chemical beam epitaxy (CBE) of InAs dots on GaAs(100) tilted 2° off toward the nearest (110). Atomic force microscope images and transmission electron microscope (TEM) photographs showed that highly uniform dots were grown in the Stranski-Krastanow growth mode. An average dot density of ∼10 ¹⁰ cm ^-2 was obtained by changing the deposition thickness. The shape of the quantum dots was initially round and then became elongated along the [Oil] direction due to the preferential growth of InAs with increasing deposition thickness. TEM and transmission electron diffraction images also showed that 90% of the strains in the InAs islands grown at a 2 ML of InAs deposition were relieved by the formation of 90° misfit dislocations in the (ill) plane, whereas the strains were not relaxed in coherently grown islands with a 1 ML of InAs deposition. CBE growth of InAs is found to produce self-assembled InAs dots or wires with quantum sizes on highly lattice-mismatched GaAs(100) substrates.