Strain-enhanced electron mobility anisotropy in InxGa1−xAs/InP two-dimensional electron gases

We systematically investigated electron mobility anisotropy in compressively strained, lattice-matched, and tensilely strained InGaAs quantum wells (QWs) grown on InP (0 0 1) by using Hall-bar devices with various current-flowing directions. Anisotropy of electron mobility, the highest along the [1 View the MathML source 0] direction and the lowest along [1 1 0], is systematically observed in all QWs, and well-fitted with a sinusoidal function of the current-flowing direction angle. The mobility anisotropy is minimum in the lattice-matched case and enhanced by both compressive and tensile strains in the QWs. We consider that random piezoelectric scattering, which is enhanced by the average normal strain in the QW, has anisotropy and plays an important role for the observed results.