G. Costantini

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By high resolution scanning tunneling microscopy, we investigate the morphological transition from pyramid to dome islands during the growth of Ge on Si(001). We show that pyramids grow from top to bottom and that, from a critical size on, incomplete facets are formed. We demonstrate that the bunching of the steps delimiting these facets evolves into the(More)
SiGe islands move laterally on a Si(001) substrate during in situ postgrowth annealing. This surprising behavior is revealed by an analysis of the substrate surface morphology after island removal using wet chemical etching. We explain the island motion by asymmetric surface-mediated alloying. Material leaves one side of the island by surface diffusion, and(More)
A novel structure containing self-assembled, unstrained GaAs quantum dots is obtained by combining solid-source molecular beam epitaxy and atomic-layer precise in situ etching. Photo-luminescence (PL) spectroscopy reveals light emission with very narrow inhomogeneous broadening and clearly resolved excited states at high excitation intensity. The dot(More)
With this report we communicate the results of a method for the fractionation of the isoenzymes of gamma-GT in human serum based on a modified technique of Hetland et al., using cellulosa acetate. With this method we observed the appearance of a complex of four band representing: gamma-GT1 = prealbumin-albumin, gamma-GT3 = alpha 1-globulin, gamma-GT3 =(More)