Effects of extreme disorder on electronic properties in delta-doped semiconductor microstructures - a realistic computer simulation

impurity induced disorder is a key feature of strongly doped semiconductor microstructures. We present a theoretical approach which allows the realist ic and efficient calculation of localized quantum states in layered, delta- doped systems and the resulting properties of the quasi-2D multisubband ele ctron/hole gas. The random Coulomb potential is directly computed from the impurity distribution without any simplifying assumptions. Electron-electro n interaction is treated self-consistently on the Hartree level. The extrem e cases of the doping superlattice (strong disorder) and the modulation dop ed quantum well (weak disorder) are studied as example device structures. I ntersubband absorption spectra are then calculated for both types of system s and studied as a function of the electron filling factor. Striking differ ences are found between the linewidths of potential fluctuations and absorp tion spectra. These results are explained on the basis of system geometry, nonlinear screening and intersubband correlations. Finally, we discuss poss ible future applications and extensions of the method. (C) 1999 Academic Pr ess.