Nonlinear Landau absorption in III-V semiconductors near the fundamental absorption edge.

Abstract

Analytical investigations have been made of nonlinear Landau absorption in important III-V semiconductors such as GaAs, GaSb, InSb, and InAs which have been irradiated by suitable lasers of photon energies (\ensuremath{\Elzxh}\ensuremath{\omega}) nearly equal to the band-gap energies (\ensuremath{\Elzxh}${\ensuremath{\omega}}_{g}$) in the presence of a large magnetostatic field. A coherent radiation-exciton interaction model has been used for the direct allowed transitions between the n=0 Landau subbands. The result obtainable for linear magnetoabsorption using the present model agrees very well with that obtained in the 1960's using a completely different approach. The effective nonlinear Landau absorption ${\ensuremath{\alpha}}^{\mathrm{nonlin}({B}_{0})}$ has been studied by examination of the imaginary part of the third-order optical susceptibility. The contributions from the higher-order susceptibilities have been neglected. The Wannier-Mott exciton wave function \ensuremath{\psi}(0) is found to play a very important role in the nonlinear Landau absorption processes as it occurs in the fourth power in the expression for ${\ensuremath{\alpha}}^{\mathrm{nonlin}({B}_{0})}$. For near-band-gap resonant excitation in the true continuum with \ensuremath{\Elzxh}(\ensuremath{\omega}-${\ensuremath{\omega}}_{g}$) less than the crystal exciton rydberg, \ensuremath{\Vert}\ensuremath{\psi}${(0)}^{2}$\ensuremath{\Vert}\ensuremath{\gg}1 and its contribution must be recognized under this regime. The renormalization of the crystal band gap due to the exciton rydberg and the light shift has also been discussed.