Investigation of Ge1-xSnx/Ge with high Sn composition grown at low temperature
Date Issued
2011
Date
2011
Author(s)
Wu, Tzung-Hsian
Abstract
We report on experimental investigations of the growth of Ge1-xSnx film with thickness above the critical thickness using Molecular Beam Epitaxy. A series of Ge1-xSnx films with various Sn compositions up to 14% are deposited on a Ge buffer layer for growth at low temperatures close to the melting point of Sn. Especially, a low temperature Ge buffer layer was grown between GeSn film and Ge substrate for
trapping defects. Analysis of various measurements shows that the Ge1-xSnx film is defect free in the XTEM image and that Sn is distributed almost uniformly in the film for Sn compositions up to 9.3%. The Sn composition of the films is higher than the Sn composition that is theoretically predicted to cause the energy band of Ge to change from an indirect to a direct bandgap; thus, the present nvestigation provides a method for growing direct bandgap GeSn film, which is desired for use in applications involving optoelectronic devices.
Subjects
MBE
GeSn alloy
direct bandgap
TEM
Type
thesis
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