Subband optical absorption in lateral-surface superlattices under normally applied electric fields

We perform numerical calculations to predict the electronic energy-subband structures in quasi-two-dimensional electronic systems with periodic modulation potentials along the lateral directions under normally applied electric fields. These potentials arise from the periodic modulation of the widths of the systems, such as those produced by deposition of AlAs and GaAs fractional layers on (001) vicinal GaAs substrates. A coordinate transformation was introduced which transforms the systems with periodically structured interfaces to quantum wells with planar interfaces so that the boundary conditions of the electron wave functions are considerably simplified. Far-infrared optical absorptions associated with the electron transitions between the electron conduction subbands of the systems were predicated numerically. The changes of the electronic density of states, energy minigaps, and subband optical-absorption coefficients as functions of the normally applied electric fields are investigated in detail.