Anisotropic shape of self-assembled InAs quantum dots: Refraction effect on spot shape of reflection high-energy electron diffraction

A significant role of refraction effect on reflection high-energy electron diffraction (RHEED) from nanostructures is demonstrated. It was found that the chevron-shape spots in RHEED patterns from self-assembled InAs/GaAs(001) and InAs/InAlAs/InP(001) quantum dots at $\left[11¯0\right]$ azimuth are well reproduced by kinematical calculations taking into account the refraction of electron beam at the curved surfaces of the dots. The dots must have $\left(11\mathrm{}¯0\right)$ cross sections steeper than (110) cross sections and consequently extend along $\left[11¯0\right]$ since the refraction effects, considerable only at glancing incidence and departure, are invisible at [110] azimuth.