Electron scattering by native defects in uniformly and modulation doped semiconductor structures.

摘要

Formation of native defects in GaAs is described in terms of the amphoteric native defect model. It is shown that Fermi energy induced formation of gallium vacancies is responsible for the limitations of maximum free electron concentration in GaAs. The effect of the defects on electron mobility in heavily doped n-GaAs is quantitatively evaluated. Defect scattering explains the abrupt reduction of electron mobility at high doping levels. Also, it is demonstrated that native defects are responsible for the mobility reduction in inverted modulation doped GaAs/AlGaAs heterostructures. The amphoteric defect model also explains a distinct asymmetry in defect formation in n- and p-GaAs. In p-GaAs the Fermi level induced reduction of the defect formation energy is much smaller, and therefore the concentration of the native defects is negligible compared with the hole concentration. 43 refs., 5 figs.