|approved||osi__11__2hg_nearfield_with_picture_abstract_farbod_shafiei.pdf||2015-06-12 18:46:49||Farbod Shafiei|
Author: Farbod Shafiei
Requested Type: Oral
Submitted: 2015-03-27 11:22:20
Co-authors: Yujin Cho,Tommaso Orzali, Gennadi Bersuker, Micheal Downer
The University of Texas at Austin
Austin, Texas 78712
Growth of III-V semiconductor films on Si substrates has long been of interest for integrating the high carrier mobility and light-emitting properties of III-Vs into the mainstream Si platform. However, polar-on-nonpolar hetero-epitaxial films are susceptible to formation of submicron anti-phase domains (APDs) that compromise film quality. Recently, substrate-patterning techniques have shown promise for suppressing APDs . The resulting renewing interest in the III-V/Si system has prompted demand for non-invasive, in-situ methods capable of characterizing APDs during growth, and distinguishing them from threading dislocations. Recently we showed that SHG is highly and selectively sensitive to submicron APDs , since X(2) reverses sign in neighboring domains, leading to destructive interference in the far field. However, individual APDs were not resolved. Here we report successful implementation of SHG near-field optical microscopy (NSOM) that fully resolves individual APDs and their boundaries. Using SHG microscopy, we have discovered substrate patterns that are effective in suppressing APDs. SHG microscopy can also image domains in ferroelectric materials, and probe unique properties of domain walls . We will present initial SHG images of improper double-perovskite ferroelectric domains.
 Li, J. Cryst. Growth 311, 313 (2009);  Lei, APL 102, 152103 (2013);  S. Faroukhipoor, Nature 515, 379 (2014).