Growth and Characterization of Inas Quantum Dots on Silicon

Abstract

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.

Growth and Characterization of InAs Quantum Dots on Silicon

“…(001) substrates were hydrogenpassivated, details on their preparation and optimized growth conditions can be found in [9,10]. (001) substrates were hydrogenpassivated, details on their preparation and optimized growth conditions can be found in [9,10].…”

“…1b). [10] on the basis of a simple thermodynamic model which mainly considers the additional strain energy to the Gibbs free energy of the heteroepitaxial system [12]. The growth mode transition is accompanied by a more and more blurred 2D RHEED image and finally a change towards a spotty 3D image.…”

“…This (irreversible) dewetting transition is explained by the thermodynamic model in [10]. When reducing the substrate temperature from 370 C to approximately 320-300 C after growth, the 2D layer gets thermodynamically unstable and a spotty RHEED image indicates an abrupt transition into 3D islands.…”

“…So far, the problem arises that reflection high energy electron diffraction (RHEED), Raman spectroscopy and transmission electron microscopy (TEM) indicate that after the 2D/3D growth mode transition of InAs on Si the InAs QDs are fully relaxed with the inclusion of misfit dislocations. A dewetting transition of a single monolayer (ML) of InAs during the postgrowth lowering of the temperature has been observed and was described on the basis of a thermodynamic model in [10]. Besides that, the investigation of QD growth on differently terminated silicon substrates is believed to give new insights into the physics of self-organization in the InAs/ Si system.…”

Formation of InAs/GaAs quantum dots by dewetting during cooling

“…This phenomenon has previously been observed for MBE growth of InAs on Si. 6 Hansen et al deposited 1.5 monolayers of InAs on Si at 370°C and then cooled the sample. Below 320°C, they discovered that islands formed, and the size distribution of the islands was unusual.…”