THEORETICAL INVESTIGATION OF THE PHOTOLUMINESCENCE AND FERMI-SURFACE OF PERIODICALLY DELTA-DOPED GAAS

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 emissi on band at energies above the GaAs band edge. The experimentally obtai ned photoluminescence lineshape is well reproduced by the theory. The calculated cut-off energy in the photoluminescence spectrum is in exce llent agreement with the experimental value. The Fermi surface is stud ied as a function of the doping period. The gradual change in the Ferm i surface, which occurs when the spacing between the dopant sheets dec reases, provides a clear-cut description of the crossover from two- to three-dimensional electronic structure in delta-doped GaAs. The respo nse of the system to a magnetic field, applied in the plane of the lay ers, is considered, and the condition of magnetic breakdown is studied .