Transport properties of selectively doped GaAs-(AlGa)As heterostructures grown by molecular beam epitaxy

Abstract

In selectively doped GaAs-(AlGa)As heterostructures the two-dimensional (2D) electron density is found to be monotonically decreasing with increasing separation (t0) between the mobile carriers and the doped (AlGa)As layer. A quantitative description of this t0 dependence requires the Si dopant to create a deep center in (Al0.3Ga0.7)As. For t0≳60 Å the low-temperature electron mobility, which can be as high as 1.6×106 cm2/Vs, does not show a correlation with t0. Unidentified and as yet uncontrollable impurities in the vicinity of the 2D system are a likely source for the residual electron scattering.