Microstructural characterization of quantum dots with type-II band alignments

We are investigating the structural, electrical, and infrared (IR) optical properties of a new material system comprising undoped self-assembled quantum dots having a type-II band alignment with the surrounding matrix. This materials system is fundamentally different from those using conventional type-I quantum dots that must be doped and that rely on intersubband transitions for IR photoresponse. Type-II quantum dots operate in the photovoltaic mode with IR photoresponse arising from electron–hole pair production involving three-dimensionally confined states in the dots and quantum well states in the matrix material. In this paper, we discuss the structural characterization of molecular beam epitaxy (MBE)-grown InSb quantum dots embedded in an In0.53Ga0.47As matrix lattice-matched to an InP substrate.