Dislocation and antiphase domain free microscale GaAs crystals grown on SiO2 from (001) Si nano-areas

The epitaxial lateral overgrowth of microscale GaAs crystals on a 0.6nm thick SiO2 layer from nanoscale Si seeds is investigated in order to develop GaAs monolithic hetero-epitaxy onto (001) Si. The nucleation from small width openings enables to avoid the emission of misfit dislocations and the formation of antiphase domains. Consequently, the interface between the GaAs island and the SiO2 layer remains perfectly sharp and free of defects. The only defects found by transmission electron microscopy in each island are pairs of twins, and a simple model based on the anisotropy of zinc blende crystal is proposed to explain their formation. Micro-photoluminescence measurements performed at room temperature show that these twins are not detrimental for the quality of microscale GaAs crystals. (C) 2013 AIP Publishing LLC.