DOPING CHARACTERISTICS OF UNDOPED AND ZN-DOPED IN(GA)ALAS LAYERS GROWN BY LOW-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY

Doping properties of undoped and Zn-doped In(Ga)AlAs layers grown lattice-matched on InP by low-pressure metalorganic vapour phase epitaxy (MOVPE) were investigated. In non-intentionally doped InAlAs, oxygen proves to be the dominant impurity the incorporation of which was, however, found to strongly depend on the V/111 ratio. Background doping levels as low as 2 x 10(15) cm-3 were achieved in these layers. Zn-doping in InAlAs is incorporation-limited to a level of about 3 x 10(18) cm-3, but increases with decreasing Al content in InGaAlAs. The diffusivity of Zn during growth appears to be favourably lower in InAlAs as compared to InP. Finally, the well-known effect of acceptor passivation was not encountered with the present MOVPE conditions.