Anisotropic scattering of elongated GaSb/GaAs quantum dots embedded near two-dimensional electron gas

Geometrically anisotropic GaSb/GaAs quantum dots elongated along [110] direction, with a lateral aspect ratio of 2-3, are embedded in the vicinity of AIGaAs/GaAs two-dimensional electron gas, using the molecular beam epitaxy by carefully controlling the Sb4 beam flux and As4 background pressure. The electron mobilities micro parallel, micro perpendicular parallel and perpendicular to the direction of dot elongation axis are measured as functions of electron concentration n(2D) at 4.2 K, respectively. As the increase of n(2D), the mobility discrepancy (micro parallel-micro perpendicular) is found to be getting larger. This mobility difference is believed to be due to the anisotropic scattering potential of the elongated GaSb quantum dots. Under Born approximation, we propose a model with the constant squared-barrier potential to calculate the n(2D) dependence of mobility and reasonable agreement is achieved between the experimental results and theoretical simulation.