Heteroepitaxial growth of InAs on GaAs(0 0 1) by in situ STM located inside MBE growth chamber

The growth of InAs on GaAs(0 0 1) is of great interest primarily due to the self-assembly of arrays of quantum dots (QDs) with excellent opto-electronic properties. However, a basic understanding of their spontaneous formation is lacking. Advanced experimental methods are required to probe these nanostructures dynamically in order to elucidate their growth mechanism. Scanning tunneling microscopy (STM) has been successfully applied to many GaAs-based materials grown by molecular beam epitaxy (MBE). Typical STM–MBE experiments involve quenching the sample and transferring it to a remote STM chamber under arsenic-free ultra-high vacuum. In the case of GaAs-based materials grown at substrate temperatures of 400–600 °C, operating the STM at room temperature ensures that the surface is essentially static on the time scale of STM imaging. To attempt dynamic experiments requires a system in which STM and MBE are incorporated into one unit in order to scan in situ during growth. Here, we discuss in situ STM results from just such a system, covering both QDs and the dynamics of the wetting layer.