Electron mobility anisotropy in InAs/GaAs(001) heterostructures

Electron transport properties in InAs films epitaxially grown on GaAs(001), InAs/GaAs(001) heterostructures, were systematically investigated through the dependence on crystal direction, thickness, and temperature. As a result, we found a pronounced electron mobility anisotropy, in which the mobility is highest and lowest along [ 1 1 ¯ 0 ] and [ 110 ] crystal directions, respectively. The mobility anisotropy intensifies as the InAs thickness decreases, while it diminishes in thick regimes, where the InAs films are relatively immune to effects from the epitaxial heterointerface. We observed the anisotropy in a wide temperature range, 5–395 K, with an enhancement at high temperatures. Our analysis indicates that the electron mobility anisotropy can be attributed to anisotropic electron scatterings by both interface roughness and random piezoelectric polarization near the interface.