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Title: Heterogeneous nucleation of pits via step pinning during Si(100) homoepitaxy

Using scanning tunneling microscopy (STM), we investigate oxide-induced growth pits in Si thin films deposited by molecular beam epitaxy. In the transition temperature range from 2D adatom islanding to step-flow growth, systematic controlled air leaks into the growth chamber induce pits in the growth surface. We show that pits are also correlated with oxygen-contaminated flux from Si sublimation sources. From a thermodynamic standpoint, multilayer growth pits are unexpected in relaxed homoepitaxial growth, whereas oxidation is a known cause for step-pinning, roughening, and faceting on elemental surfaces, both with and without growth flux. Not surprisingly, pits are thermodynamically metastable and heal by annealing to recover a smooth periodic step arrangement. STM reveals new details about the pits' atomistic origins and growth dynamics. Here, we give a model for heterogeneous nucleation of pits by preferential adsorption of Å-sized oxide nuclei at intrinsic growth antiphase boundaries, and subsequent step pinning and bunching around the nuclei.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Lab. for Physical Sciences, College Park, MD (United States)
Publication Date:
Report Number(s):
SAND-2017-11273J
Journal ID: ISSN 1367-2630; 657902; TRN: US1703263
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 19; Journal ID: ISSN 1367-2630
Publisher:
IOP Publishing
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; thin film; molecular beam epitaxy; scanning tunneling microscopy; Si(100); oxide; growth pit; defect; impurity
OSTI Identifier:
1406367