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FM Ross

Publications and source records attributed to FM Ross.

7 recordsLinked to original sources
PubMed2000

Instability-driven SiGe island growth

Three-dimensional islanding is generally assumed to proceed through nucleation and growth. Here we present studies showing the growth of Si1-xGex islands (0.2<x<0.6) without nucleation. Rather, a strain-driven growth instability induces a network of elevated cells, where the angle of elevation self-limits when 105 facets form pyramidal islands. These strain-modulated surfaces may serve as a template for the spatially controlled growth of quantum dot ensembles.

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PubMed2000

New mechanism for dislocation blocking in strained layer epitaxial growth

Dislocation interactions play a critical role in plasticity and heteroepitaxial strain relaxation. We use real time transmission electron microscopy observations of the interaction between threading and misfit dislocations in SiGe heterostructures to investigate interactions quantitatively. In addition to the expected long-range blocking of threading segments, we observe a new short-range mechanism which is significantly more effective. Simulations show that this reactive blocking occurs when two dislocations with the same Burgers vector reconnect.

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PubMed1999

Transition States Between Pyramids and Domes During Ge/Si Island Growth.

Real-time observations were made of the shape change from pyramids to domes during the growth of germanium-silicon islands on silicon (001). Small islands are pyramidal in shape, whereas larger islands are dome-shaped. During growth, the transition from pyramids to domes occurs through a series of asymmetric transition states with increasing numbers of highly inclined facets. Postgrowth annealing of pyramids results in a similar shape change process. The transition shapes are temperature dependent and transform reversibly to the final dome shape during cooling. These results are consistent with an anomalous coarsening model for island growth.

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PubMed1998

Ostwald Ripening of Self-Assembled Germanium Islands on Silicon(100).

: We describe here real-time, in situ observations of the formation of nanosize germanium (Ge) islands on silicon (Si). The deposition of Ge onto electron-transparent Si(100) takes place in a UHV transmission electron microscope that has been modified to allow chemical vapor deposition to be carried out in the polepiece. We recorded the growth process at video rate and were therefore able to follow the evolution of individual islands. As the islands grew, we observed a coarsening process similar to classical Ostwald ripening, but which leads at certain times to a bimodal distribution of island sizes. We show that this phenomenon can be understood using a model in which a conventional coarsening process is modified by a transition between two different island shapes.

Journal Article↗