Extrinsic layer at AlxGa1−xAs-GaAs interfaces

Abstract

Photoluminescence studies of GaAs-AlxGa1−xAs heterostructures grown by molecular beam epitaxy (MBE) which contain one and two GaAs quantum wells suggest that in some of the samples the first well grown usually exhibits a ’’rough’’ (6 Å≲δL≲15 Å) first interface and an acceptorlike luminescing impurity in the first few tens of angstroms of GaAs grown. The luminescence may arise from carbon which accumulates on the AlxGa1−xAs -vacuum interface during growth and is then deposited in the first few unit cells of GaAs. The phenomenon discussed may be relevant to the problem of growing high electron mobility field-effect transistor heterostructures by MBE with GaAs on the top.