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Title: Probing Surface Chemistry at an Atomic Level: Decomposition of 1-Propanethiol on GaP(001) (2 × 4) Investigated by STM, XPS, and DFT

Abstract

The adsorption and decomposition mechanisms for 1-propanethiol on a Ga-rich GaP(001) (2 × 4) surface are investigated at an atomic level using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations. Using a combination of experimental and theoretical tools, we probe the detailed structures and energetics of a series of reaction intermediates in the thermal decomposition pathway from 130 to 773 K. At 130 K, the propanethiolate adsorbates are observed at the edge gallium sites, with the thiolate–Ga bonding configuration maintained up to 473 K. Further decomposition produces two new surface features, Ga–S–Ga and P-propyl species at 573 K. Finally, S-induced (1 × 1) and (2 × 1) reconstructions are observed at 673–773 K, which are reportedly associated with arrays of surface Ga–S–Ga bonds and subsurface diffusion of S. To understand the observed site-selectivity on the hydrogen dissociation of the thiol molecule at 130 K, the two most likely dissociation pathways (Ga–P vs Ga–Ga dimer sites) are investigated using DFT Gibbs energy calculations. While the theory predicts the kinetic advantage for the dissociation reaction occurring on the Ga–P dimer (Lewis acid–base combination), we only observed dissociation products on the Ga–Ga dimer (Lewis acid). Here, the DFTmore » calculations clarify that the reversible thiolate diffusion along the Ga dimer row prevents recombinative desorption, which is probable on the Ga–P dimer. Together with experimental and theoretical results, we suggest a thermal decomposition mechanism for the thiol molecule with atomic-level structural details.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [1]; ORCiD logo [2]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  2. Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1560408
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 123; Journal Issue: 5; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; II-V semiconductor; gallium phosphide (GaP); alkanethiol; scanning tunneling microscope; X-ray photoelectron spectroscopy; density functional theory

Citation Formats

Jeon, Seokmin, Kim, Minho, Doak, Peter W., Atwater, Harry A., and Kim, Hyungjun. Probing Surface Chemistry at an Atomic Level: Decomposition of 1-Propanethiol on GaP(001) (2 × 4) Investigated by STM, XPS, and DFT. United States: N. p., 2019. Web. doi:10.1021/acs.jpcc.8b10993.
Jeon, Seokmin, Kim, Minho, Doak, Peter W., Atwater, Harry A., & Kim, Hyungjun. Probing Surface Chemistry at an Atomic Level: Decomposition of 1-Propanethiol on GaP(001) (2 × 4) Investigated by STM, XPS, and DFT. United States. doi:10.1021/acs.jpcc.8b10993.
Jeon, Seokmin, Kim, Minho, Doak, Peter W., Atwater, Harry A., and Kim, Hyungjun. Fri . "Probing Surface Chemistry at an Atomic Level: Decomposition of 1-Propanethiol on GaP(001) (2 × 4) Investigated by STM, XPS, and DFT". United States. doi:10.1021/acs.jpcc.8b10993.
@article{osti_1560408,
title = {Probing Surface Chemistry at an Atomic Level: Decomposition of 1-Propanethiol on GaP(001) (2 × 4) Investigated by STM, XPS, and DFT},
author = {Jeon, Seokmin and Kim, Minho and Doak, Peter W. and Atwater, Harry A. and Kim, Hyungjun},
abstractNote = {The adsorption and decomposition mechanisms for 1-propanethiol on a Ga-rich GaP(001) (2 × 4) surface are investigated at an atomic level using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations. Using a combination of experimental and theoretical tools, we probe the detailed structures and energetics of a series of reaction intermediates in the thermal decomposition pathway from 130 to 773 K. At 130 K, the propanethiolate adsorbates are observed at the edge gallium sites, with the thiolate–Ga bonding configuration maintained up to 473 K. Further decomposition produces two new surface features, Ga–S–Ga and P-propyl species at 573 K. Finally, S-induced (1 × 1) and (2 × 1) reconstructions are observed at 673–773 K, which are reportedly associated with arrays of surface Ga–S–Ga bonds and subsurface diffusion of S. To understand the observed site-selectivity on the hydrogen dissociation of the thiol molecule at 130 K, the two most likely dissociation pathways (Ga–P vs Ga–Ga dimer sites) are investigated using DFT Gibbs energy calculations. While the theory predicts the kinetic advantage for the dissociation reaction occurring on the Ga–P dimer (Lewis acid–base combination), we only observed dissociation products on the Ga–Ga dimer (Lewis acid). Here, the DFT calculations clarify that the reversible thiolate diffusion along the Ga dimer row prevents recombinative desorption, which is probable on the Ga–P dimer. Together with experimental and theoretical results, we suggest a thermal decomposition mechanism for the thiol molecule with atomic-level structural details.},
doi = {10.1021/acs.jpcc.8b10993},
journal = {Journal of Physical Chemistry. C},
number = 5,
volume = 123,
place = {United States},
year = {2019},
month = {1}
}

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