Undoped GaAs layers, grown onto Si substrates by using the conformal method, were studied by means of micro-Raman spectroscopy, cathodoluminescence and dilute Sirtl solution with light etching. The results showed that non-intentional doping of conformal layers could take place near to the seed/layer interface. The self-doped area yielded a bright luminescence emission and exhibited longitudinal optic-plasmon coupled Raman modes. The non-intentional dopants were n-type, as deduced from Raman spectroscopy and dilute Sirtl solution with light etching. The doped region extended to only 2 or 3µm from the seed, and was tentatively associated with an enhanced diffusion of Si in the presence of dislocations at the interface between the seed and the conformal layer.

Self-Doping Near the Seed/Layer Interface in Conformal GaAs Layers Grown on Si. A.M.Ardila, O.Martínez, M.Avella, J.Jiménez, B.Gérard, J.Napierala, E.Gil-Lafon: Applied Physics Letters, 2001, 79[9], 1270-2