Type II broken-gap quantum wires and quantum dot arrays: A novel concept for self-doping semiconductor nanostructures

Abstract

A novel concept for creating self-doping quantum wires and quantum dot arrays based upon the InAs-GaSb material system is proposed. The unusual type II, broken-gap band line-up in this system allows charge transfer across the InAs-GaSb interfaces. We employ a recently developed coupled band formalism to examine analytically the band structure of InAs-GaSb quantum dots and wires. The analysis shows that appropriately engineered nanostructures which contain high free-carrier densities are possible without intentional impurity doping. Quantum dots in this system behave as artificial quasiatoms, with ionization energy and valence determined by fabricationally determined parameters. Synthetic p-(n-)type semiconductors may therefore be formed from arrays of InAs(GaSb) quantum dots embedded in GaSb(InAs). InAs-GaSb quantum wires are also investigated and found to exhibit self-doping behavior. Possible fabrication schemes utilizing recently developed technologies are discussed.