Theoretical investigation of the photoluminescence and Fermi surface of periodically delta -doped GaAs

Abstract

A theoretical study of the electronic structure of periodically delta -doped GaAs is presented. When the doping period is reduced, minibands are formed, and the photoluminescence spectrum presents a broad emission band at energies above the GaAs band edge. The experimentally obtained photoluminescence lineshape is well reproduced by the theory. The calculated cut-off energy in the photoluminescence spectrum is in excellent agreement with the experimental value. The Fermi surface is studied as a function of the doping period. The gradual change in the Fermi surface which occurs when the spacing between the dopant sheets decreases, provides a clear-cut description of the crossover from two- to three-dimensional electronic structure in delta -doped GaAs. The response of the system to a magnetic field, applied in the plane of the layers, is considered, and the condition of magnetic breakdown is studied.