Correlation of buffer strain relaxation modes with transport properties of two-dimensional electron gases

Abstract

We have investigated the effects of buffer strain relaxation on the transport properties of two-dimensional electron gases (2DEGs). The 2DEGs consist of modulation-doped In0.53Ga0.47As/In0.52Al0.48As heterostructures grown lattice-mismatched to GaAs via compositionally step-graded InxGa1−xAs buffers, with different composition gradients, or lattice-matched to InP. We find a variation in 2DEG electronic properties which occurs simultaneously with large differences in epilayer tilt and mosaic spread in the step-graded buffers. This indicates a correlation between the mechanism of buffer strain relaxation and the 2DEG transport properties.