Nanovoids in InGaAs∕GaAs quantum dots observed by cross-sectional scanning tunneling microscopy

Abstract

We present cross-sectional scanning tunneling microscopy data of a type of InGaAs∕GaAs quantum-dot structure characterized by a hollow center. This void structure develops during a long growth interruption applied after deposition of a quantum dot layer and a thin cap layer, resulting in an eruption of indium-rich material. Subsequent fast overgrowth does not fill the void completely. This growth behavior demonstrates limitations of current strategies to grow large quantum dots.