Investigation of the optical and electrical structure of Al_1-xIn_xN alloys: a DFT study

Abstract The electrical structure and optical properties of the Al 1− x In x N alloys were calculated via DFT calculations as a function of the indium content. To combine aluminum nitride (AlN) and indium nitride (InN), aluminum is partly substituted by indium in an AlN matrix. Our results reveal that increasing the indium content reduces the energy gap of the (AlInN) alloy. The alloy has an equivalent number of electronic states at each energy level for both spin directions. This means that the structures of Al1- x In x N are nonmagnetic materials. The optical calculations indicated that the absorption peaks of indium-doped AlN shifted toward lower energy (redshift) because of the reduction in the energy gap. As the indium concentration increases, the shift becomes more apparent, moving the absorption peak further into the visible or near-infrared region. Additionally, doping AlN with indium shifts the peak of the imaginary dielectric function toward lower energies due to energy gap reduction. Phonon dispersion calculations stated that all the studied structures of Al 1− x In x N for different In content are stable.