The characterization of crystal defects in GaAs layers, grown onto Si substrates by using the conformal growth method, was described. The technique involved GaAs lateral

growth from GaAs seeds confined between the Si substrate and an overhanging dielectric cap layer. These conformal layers grew with a reduced density of crystal defects (such as dislocations) which were effectively filtered out by the particular geometrical configuration. The samples were analyzed by means of micro-Raman spectroscopy, cathodoluminescence and phase-stepping microscopy, and were etched in dilute Sirtl solution; applied with light. Several structures were revealed, such as a quasi-periodic array of hillocks and valleys that were spatially correlated with fluctuations in the luminescence intensity.

Study of Defects in Conformal GaAs/Si Layers by Optical Techniques and Photoetching. A.M.Ardila, O.Martínez, L.F.Sanz, M.Avella, J.Jiménez, J.Napierala, E.Gil-Lafon, B.Gérard: Materials Science and Engineering B, 2002, 91-92, 70-4