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InAs quantum dots (QD) embedded in a silicon matrix show a photoluminescence line at a wavelength of about 1.3 µm [Semicond. Sci. Technol. 13 (1998) 1262]. This wavelength range is very interesting for the integration of classical silicon technology with optical fiber applications for chip-to-chip or intra-chip communication. To get InAs QDs of reproducible size and shape the growth conditions for the formation of quantum dots have to be optimized. Here, we report on detailed investigations on the molecular beam epitaxial growth of InAs QDs on silicon and their embedding in a silicon matrix. A variety of surface analytical techniques have been used, including in-situ electron diffraction (RHEED), in-situ photoelectron spectroscopy (XPS) and ex-situ atomic force microscopy (AFM).

We present a comprehensive investigation of molecular beam epitaxial (MBE) grown InAs quantum dots (QD) on silicon (001) and (111) by reflection high energy electron diffraction (RHEED) and Raman spectroscopy in UHV environment and ex-situ by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Two different ways were developed to prepare up to 10 11 cm --2 InAs QDs on Si(001). One is the conventional mode by exceeding a critical thickness of deposition at which 2D growth changes towards a 3D growth mode. A second way is a dewetting transition, induced by cooling an approximately 1 ML thin 2D InAs layer from growth temperature below a critical temperature at which RHEED indicates the formation of nanoislands. Samples grown in both manners show significant differences in morphology and shape though RHEED, TEM and Raman studies correspondingly indicate strain relaxation. On Si(111) InAs grows in the common temperature range for InAs growth ($400 C) in flat clusters separated by deep trenches. A previous passivation of the Si(111) surface with arsenic at~700 C on the other hand leads to the formation of large InAs nanocrystals.

Up to 1011 cm−2 InAs quantum dots (QD) can be grown on Silicon(001) by molecular beam epitaxy. This very new material system is on the one hand interesting with regard to the integration of optoelectronics with silicon technology on the other hand it offers new insight into the formation of QDs. We report on RHEED, TEM and Raman studies about (in-) coherence of the QDs and on an according to our knowledge so far unknown dewetting transition in this material system. The results are being discussed on the basis of a thermodynamic model, assuming a liquid-like behavior of a strained adlayer.