CHARACTERISTICS OF SI DOPED GAAS GROWN ON (111)A, B AND (100) SUBSTRATES BY MBE IN RELATION TO LATTICE LOCATION OF SI

Si-doped GaAs grown on (111)A, B and (100) oriented substrates by MBE was characterized by C-V, Hall, SIMS, photoluminescence, Raman scattering and XFR measurements. Above [Si] approximately 6 x 10(18) cm-3 the electron concentration of (111)B layers saturates and then decreases, and deep PL band appears as in the case of (100) growth, where these phenomena have been explained by the formation of Si(Ga)-complexes. On the contrary, for (111)A growth, doped Si atoms occupy As sites and act as acceptors with no deep level emission up to [Si] approximately 6 x 10(19)cm-3. At higher doping concentration, Si starts to occupy Ga sites resulting in the saturation of carrier density by autocompensation mechanism and, at much higher concentration, the formation of Si(Ga)-complexes takes place.