Short range scattering mechanism of type-II GaSb/GaAs quantum dots on the transport properties of two-dimensional electron gas

摘要

We have studied the scattering process of AlGaAs/GaAs two-dimensional electron gas with the nearby embedded GaSb/GaAs type-II quantum dots (QDs) at low temperature. Quantum Hall effect and Shubnikov–de Haas oscillation were performed to measure the electron density n2D, the transport lifetime τt, and the quantum lifetime τq under various biased gate voltage. By comparing measured results of QDs sample with that of reference sample without embedded QDs, mobilities (transport mobility μt and quantum mobility μq) dominated by GaSb QDs scattering were extracted as functions of n2D. It was found that the ratios of τt to τq were varying within the range of 1–4, implying the scattering mechanism belonging to the sort of short-range interaction. In the framework of Born approximation, a scattering model considering rectangular-shaped potential with constant barrier height was successfully applied to explain the transport experimental data. In addition, an oscillating ratio of τt/τq with the increasing n2D was predicted in the model.