Nonlinear intersubband optical absorption of Si delta-doped GaAs under an electric field

Yildirim, Hasan
Tomak, Mehmet
We study the nonlinear intersubband optical absorption of a single Si delta-doped GaAs sheet placed in the middle of a GaAs quantum well and subjected to an electric field. The Schrodinger and Poisson equations are solved self-consistently for various electric field strengths. The self-consistent solutions provide us with the correct confining potential, the wave functions, the corresponding subband energies and the subband occupations. The nonlinear optical intersubband absorption spectra are discussed within the framework of the density matrix formulation for various electric field strengths, well widths, and sheet thicknesses in which Si atoms are distributed uniformly. We include both the depolarization and exciton shifts in calculations. The depolarization effect not only shifts the peak value but also makes the nonlinear absorption spectrum strongly asymmetric with the increasing intensity of the optical field. The blue-shift associated with the depolarization shift is decreased when the intensity is increased. The absorption line shape becomes more asymmetric at smaller well widths and thicker doping layers. The electric field, restores the symmetry of the absorption line shape at larger well widths and thinner doping layers, but it decreases the peak value of the line shape. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.