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 GaAs_1−xN_x/GaAs_1−yN_y 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 GaAs_1−xN_x over layer falls completely inside the band gap of the substrate GaAs_1−yN_y 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 GaAs_1−yN_y which is fully inside the band gap of the GaAs_1−xN_x over layer. Besides the CBO, the VBO and the relaxed/strained band gap of two particular cases: GaAs_1−xN_x/GaAs and GaAs_1−xN_x/GaAs_0.98N_0.02 heterointerfaces have been determined.