TAILORING OF SI DOPING LAYERS IN GAAS DURING MOLECULAR-BEAM EPITAXY

For Si delta-like doping of GaAs lateral ordering processes and segreg ation in growth direction have been investigated in real time by monit oring longe-range and short-range ordering effects using reflection hi gh-energy electron diffraction (RHEED) and reflectance anisotropy spec troscopy (RAS). When Si is supplied in pulses to GaAs(001) distinct or dering processes occur which are promoted by misorientation steps on t he vicinal surface. The incorporation of Si atoms on Ga sites in a sin gle plane can be completed to a high degree. The depth profile of the electron concentration is closely related to Si segregation during GaA s overgrowth. In the case of a doping layer of extremely high coverage it shows a minimum at the centre of the doping spike. For samples gro wn on vicinal GaAs(001) surfaces under conditions favourable for wire- like Si incorporation a considerable enhancement of the exciton photol uminescence (PL) intensity and decay time has been found.