Two-photon absorption in GaN, GaInN, and GaAlN alloys

Abstract

We have carried out full band-structure-based studies of two-photon absorption coefficients in the GaN compound, and GaInN and GaAlN alloys. An accurate Hamiltonian and resulting wave functions and band structures are used in the calculations. The coefficients in GaN calculated without any adjustable parameters agree very well with recent experiments. We further show that the two-photon absorption coefficients can be increased or decreased by adding In or Al to the GaN compound. The spectral variation of the absorption coefficient can be explained in terms of the alloy-induced changes in the band gap and joint density of states.