Short range scattering mechanism of type-ll 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 n_(2D), the transport lifetime τ_t, and the quantum lifetime τ_q under various biased gate voltage. By comparing measured results of QDs sample with that of reference sample without embedded QDs, mobilities (transport mobility μ_t and quantum mobility μ_q) dominated by GaSb QDs scattering were extracted as functions of n_(2D). It was found that the ratios of τ_t to τ_q 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 τ_t/τ_q with the increasing n_(2D) was predicted in the model.