Local strain in silicon nanomembranes and its impacts on quantum dot growth.

摘要

Nanomembrane materials are very thin sheets of single crystal material with thicknesses as thin as a few nanometers or as thick as a few hundred nanometers. The ease with which nanomembranes can be strained also makes them a uniquely responsive substrate for the growth of strained epitaxial quantum dots (QDs). I study the epitaxial growth of strained Ge QDs on Si nanomembranes (SiNMs) and observe a new self-organizing growth regime when QDs are grown on both sides of a freestanding Si nanomembrane (SiNM). Because the SiNM can accommodate a great deal of strain locally in the region adjacent to the QD, I propose the use of QD nanostressors grown periodically on a Si nanoribbon as a method of creating a mechano-electronic super-lattice nanoribbon for potential use as a thermoelectric material. I also develop a technique combining x-ray absorption spectroscopy (XAS) with photoemission electron microscopy (PEEM) to study the local band structure of SiNMs under local strain.