Figure 2

HRTEM images of the InAs/GaAs QD with the GaAs thin film capping layer. (A) HRTEM image showing a single QD of InAs buried in the GaAs buffer layer. (B) Fast flourier transformation (FFT) image of (A) providing electron diffractions of both GaAs and InAs phases. (C) Indexing of the FFT image indicating a typical molecular beam epitaxy orientation (cubic parallel orientation) between InAs and GaAs viewed at the direction $\left[0\overline{1}1\right]$. (D) An inverse FFT (IFFT) image formed by (111) diffraction spots. (E) IFFT image of InAs QD exhibits planar mismatch and dislocations marked by T symbol. (F) IFFT image of GaAs wetting layer exhibits lattice deformation and dislocations marked by T symbol. (G) HRTEM image of one small-sized QD without any dislocations.