|approved||osi_11_art_abstract_with_picture_farbod.pdf||2015-06-15 16:21:48||Farbod Shafiei|
Author: Farbod Shafiei
Requested Type: Poster
Submitted: 2015-05-29 19:16:27
Co-authors: Tommaso Orzali, Alexey Vert, Michael Downer
The University of Texas at Austin
Austin, Texas 78712
A long-range goal of semiconductor manufacturing is integration of III-V semiconductor films onto Si substrates, to exploit the high carrier mobility and light-emitting properties of III-V devices within the established Si platform. A fundamental problem with polar-nonpolar hetero-interfaces is that natural single-atom steps on the substrate precipitate formation of submicron anti-phase domains (APDs) in the epi-film, the boundaries of which scatter carriers, degrading mobility.
Nanoscale patterning of Si substrates with SiO2 pillars is an established method for suppressing threading dislocations  via aspect ratio trapping (ART). Recently evidence that ART structures may also suppress APDs has emerged . However, APD density was diagnosed invasively and indirectly via SEM.
Here we use non-invasive SHG microscopy  to diagnose APDs directly by observing effects of sign reversal of the nonlinear optical susceptibility chi(2) in neighboring domains. ART structuring of the substrate greatly enhances far-field SHG by reducing destructive interference from neighboring APDs. Nearfield scanning SHG microscopy yields additional information on local strain in the growing epi-film.
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