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Unified method for measuring entropy differences between coexisting surface phases using low energy electron microscopy

Ivanov, M ; Gomez, D. ; Hannikainen, K. ; Niu, Y. R. LU and Pereiro, J. (2022) In Physical Review Research 4(3).
Abstract

We demonstrate the ability of low energy electron microscopy (LEEM) to extract fundamental information in surface phase transitions during in situ observations of complex semiconductor surfaces. We utilize established LEEM techniques and develop a methodology that enables us to calculate the surface entropy difference using only LEEM measurements without the need for external characterization. We demonstrate the effectiveness of the unified method by monitoring the phase coexistence during the first-order transition between the c(8×2) and (6×6) phases on the surface of GaAs(001) at a range of temperatures relevant for epitaxy. The coexistence behavior with temperature and the fluctuations of phase boundaries are measured and analyzed to... (More)

We demonstrate the ability of low energy electron microscopy (LEEM) to extract fundamental information in surface phase transitions during in situ observations of complex semiconductor surfaces. We utilize established LEEM techniques and develop a methodology that enables us to calculate the surface entropy difference using only LEEM measurements without the need for external characterization. We demonstrate the effectiveness of the unified method by monitoring the phase coexistence during the first-order transition between the c(8×2) and (6×6) phases on the surface of GaAs(001) at a range of temperatures relevant for epitaxy. The coexistence behavior with temperature and the fluctuations of phase boundaries are measured and analyzed to obtain the entropy difference and stress difference between the phases. The calculated values show that the entropy difference is not large enough to stabilize the (6×6) phase with respect to the c(8×2) by itself, suggesting that the elastic relaxation during the coexistence between the two phases is necessary to stabilize the (6×6) phase.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review Research
volume
4
issue
3
article number
033163
publisher
American Physical Society
external identifiers
  • scopus:85138893306
ISSN
2643-1564
DOI
10.1103/PhysRevResearch.4.033163
language
English
LU publication?
yes
additional info
Funding Information: M.I. and J.P. would like to thank Nicolas Abadia Calvo for the helpful discussions about fluctuations analysis. The authors would like to thank David Jesson for the input and support during the initial stages of the project. The authors acknowledge support from EPSRC research Grants No. EP/P023452/1 and No. EP/N022661/1, and the National Epitaxy Facility for supplying the samples as part of Grant No. EP/N022661/1. This project also has received funding from the European Research Council's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement No. 701246. Publisher Copyright: © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
id
e5891c74-f948-4c4f-be2e-4d086afc6acd
date added to LUP
2022-12-22 11:58:34
date last changed
2022-12-22 11:58:34
@article{e5891c74-f948-4c4f-be2e-4d086afc6acd,
  abstract     = {{<p>We demonstrate the ability of low energy electron microscopy (LEEM) to extract fundamental information in surface phase transitions during in situ observations of complex semiconductor surfaces. We utilize established LEEM techniques and develop a methodology that enables us to calculate the surface entropy difference using only LEEM measurements without the need for external characterization. We demonstrate the effectiveness of the unified method by monitoring the phase coexistence during the first-order transition between the c(8×2) and (6×6) phases on the surface of GaAs(001) at a range of temperatures relevant for epitaxy. The coexistence behavior with temperature and the fluctuations of phase boundaries are measured and analyzed to obtain the entropy difference and stress difference between the phases. The calculated values show that the entropy difference is not large enough to stabilize the (6×6) phase with respect to the c(8×2) by itself, suggesting that the elastic relaxation during the coexistence between the two phases is necessary to stabilize the (6×6) phase.</p>}},
  author       = {{Ivanov, M and Gomez, D. and Hannikainen, K. and Niu, Y. R. and Pereiro, J.}},
  issn         = {{2643-1564}},
  language     = {{eng}},
  number       = {{3}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review Research}},
  title        = {{Unified method for measuring entropy differences between coexisting surface phases using low energy electron microscopy}},
  url          = {{http://dx.doi.org/10.1103/PhysRevResearch.4.033163}},
  doi          = {{10.1103/PhysRevResearch.4.033163}},
  volume       = {{4}},
  year         = {{2022}},
}