Electron tunneling in the GaAs/AlAs(111) structures with a smooth potential at heteroboundaries

Abstract

The effect of smooth interface potential on the electron tunneling in the GaAs/AlAs(111) structures with thin layers is studied using the pseudopotential method. The transition region between the structure components is represented by a half-period of the hexagonal (GaAs) 3(AlAs)3 (111) superlattice. It is shown that the allowance for the smooth potential results in a decrease in the Γ-L-mixing, Fano-resonance narrowing, and disappearance of interface states at the GaAs/AlAs(111) interface as compared to the abrupt-interface model. The shifts of the lowest Γ-and L-resonances observed for the structures with the layer thickness <2 nm amount to ∼0.1 eV, which is in good agreement with the behavior of levels in quantum wells. The transmission coefficient of electrons with the energies 0–0.5 eV above the GaAs conduction-band bottom obtained by multivalley calculation is close to that calculated with allowance for the lowest conduction band states Γ 1 (1) and Γ 1 (2) of superlattice and Γ 1 and L 1 of binary crystals. This indicates that a two-valley superlattice model of the smooth GaAs/AlAs(111) interface can be developed.