Effect of nitrogen on the electronic band structure of group III-N-V alloys

We have studied optical transitions at the {Γ} and L points of the Brillouin zone of GaNₓAs_1-x and AlyGa_1-yNₓAs_1-x alloys using photomodulation spectroscopy. For GaNₓAs_1-x with N contents between 0% and 2%, the N-induced shift of the conduction-band L minima is found to be only a fraction of the conduction-band edge shift at the {Γ} point. The measurements of AlyGa_1-yNₓAs_1-x further show that there is no correlation between the location of the X conduction-band minima and the observed E₊ and E_- transitions. The results demonstrate that the N-induced interactions between extended {Γ}, L, and X conduction-band states do not play a significant role in modification of the conduction-band structure of III-N-V alloys. The N-induced change of the conduction-band structure is predominantly influenced by the anticrossing interaction between the extended states of the {Γ} conduction band and the localized states of nitrogen.