Direct inter-conduction-subband optical absorption of thin zinc-blende-structure-semiconductor rectangular wires.

Abstract

The optical absorption in direct-inter-conduction-subband transitions has been calculated in the electric-dipole approximation for a semiconducting thin wire fabricated from zinc-blende-structure material. Due to inversion asymmetry of the microscopic crystal potential, the 2\ifmmode\times\else\texttimes\fi{}2 Hamiltonian in the spin-1/2 basis has nonvanishing off-diagonal elements. We have solved the equivalent matrix eigenvalue problem obtained by expanding the eigenvectors in an N-term double Fourier series chosen to satisfy the zero boundary conditions automatically. We have found that (1) the spin splittings are significant and are anisotropic depending on the magnitudes and orientations of the free-propagation wave vector, (2) the eigenvector is a mixture of spin states, and (3) the oscillator strengths are nonzero for the forbidden transitions. The optical-absorption spectrum for z^-polarized incident light with an energy \ensuremath{\Elzxh}\ensuremath{\omega} is discussed.