Theoretical investigation of the conduction and valence band offsets of GaAs1 x Nx/GaAs1 yNy heterointerfaces

Theoretical investigations of the conduction band offset (CBO) and valence band offset (VBO) of the relaxed and pseudo-morphically strained GaAs1 xNx/GaAs1 yNy heterointerfaces at various nitrogen concentrations (x and y) within the range 0–0.05 and along the [0 0 1] direction are performed by means of the model-solid theory combined with the empirical pseudopotential method under the virtual crystal approximation that takes into account the effects of the compositional disorder. It has been found that for y < x, the CBO and VBO have negative and positive signs, respectively, whereas the reverse is seen when y > x. The band gap of the GaAs1 xNx over layer falls completely inside the band gap of the substrate GaAs1 yNy and thus the alignment is of type I (straddling) for y < x. When y > x, the alignment remains of type I but in this case it is the band gap of the substrate GaAs1 yNy which is fully inside the band gap of the GaAs1 xNx over layer. Besides the CBO, the VBO and the relaxed/ strained band gap of two particular cases: GaAs1 xNx/GaAs and GaAs1 xNx/GaAs0.98N0.02 heterointerfaces have been determined.