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

Ivanov, Matyo, Gomez, Daniel, Hannikainen, Kennet, Niu, Yuran and Pereiro Viterbo, Juan ORCID: https://orcid.org/0000-0002-2582-3498 2022. Unified method for measuring entropy differences between coexisting surface phases using low energy electron microscopy. Physical Review Research 4 , 033163. 10.1103/PhysRevResearch.4.033163

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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 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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2643-1564
Funders:	EPSRC, European Research Council’s Horizon 2020
Date of First Compliant Deposit:	3 October 2022
Date of Acceptance:	2 August 2022
Last Modified:	07 Jun 2023 16:53
URI:	https://orca.cardiff.ac.uk/id/eprint/153015

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