Atomistic Insights for InAs Quantum Dot Formation on GaAs(001) using STM within a MBE Growth Chamber

Fourier power spectra obtained directly from STM images (see Figure) show the development of the 3× to 4× reconstruction domains, in excellent agreement with RHEED. The images elucidate the mechanism of QD nucleation; not all deposited In is initially incorporated into the lattice, providing a large supply of material to rapidly form QDs via islands containing tens of atoms. Simulations show that tiny alloy fluctuations (like atomistic point defects) in the InGaAs wetting layer are crucial in determining nucleation sites.