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Title: Highly efficient photoinduced desorption of N{sub 2}O and CO from porous silicon

Abstract

Photoinduced desorption (PID) of N{sub 2}O and CO from porous silicon (PSi) samples is reported. Both adsorbates exhibit unusually large cross sections for PID at 193 nm, up to 10{sup -15} cm{sup 2}, 2-3 orders of magnitude larger than the literature values for similar processes on flat Si. Under this UV irradiation, N{sub 2}O molecules undergo photodissociation (a competing process leading to surface oxidation) with a cross section that is 2 orders of magnitude smaller than photodesorption. In the case of CO desorption is the exclusive photodepletion mechanism. PID efficiency decreases with increasing CO coverage suggesting PID hindrance by interactions among the desorbing CO molecules leading to re-adsorption at higher coverage. The wavelength and fluence dependence measurements exclude the possibility of laser induced thermal desorption for both adsorbates. The proposed mechanism for this phenomenon is desorption induced by hot electron transfer from the substrate to the adsorbate. Enhanced lifetime of transient negative adsorbate due to stabilization by localized holes on PSi nanotips can explain the observed abnormally large PID efficiency on top of porous silicon.

Authors:
; ; ;  [1]
  1. Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)
Publication Date:
OSTI Identifier:
22105345
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 138; Journal Issue: 4; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ADSORPTION; AUGMENTATION; CARBON MONOXIDE; CROSS SECTIONS; DESORPTION; DISSOCIATION; EFFICIENCY; ELECTRON TRANSFER; INTERACTIONS; IRRADIATION; MOLECULES; NITROUS OXIDE; OXIDATION; PHOTOLYSIS; POROUS MATERIALS; SEMICONDUCTOR MATERIALS; SILICON; SUBSTRATES; SURFACES

Citation Formats

Toker, Gil, Sagi, Roey, Bar-Nachum, Shay, and Asscher, Micha. Highly efficient photoinduced desorption of N{sub 2}O and CO from porous silicon. United States: N. p., 2013. Web. doi:10.1063/1.4788959.
Toker, Gil, Sagi, Roey, Bar-Nachum, Shay, & Asscher, Micha. Highly efficient photoinduced desorption of N{sub 2}O and CO from porous silicon. United States. doi:10.1063/1.4788959.
Toker, Gil, Sagi, Roey, Bar-Nachum, Shay, and Asscher, Micha. Mon . "Highly efficient photoinduced desorption of N{sub 2}O and CO from porous silicon". United States. doi:10.1063/1.4788959.
@article{osti_22105345,
title = {Highly efficient photoinduced desorption of N{sub 2}O and CO from porous silicon},
author = {Toker, Gil and Sagi, Roey and Bar-Nachum, Shay and Asscher, Micha},
abstractNote = {Photoinduced desorption (PID) of N{sub 2}O and CO from porous silicon (PSi) samples is reported. Both adsorbates exhibit unusually large cross sections for PID at 193 nm, up to 10{sup -15} cm{sup 2}, 2-3 orders of magnitude larger than the literature values for similar processes on flat Si. Under this UV irradiation, N{sub 2}O molecules undergo photodissociation (a competing process leading to surface oxidation) with a cross section that is 2 orders of magnitude smaller than photodesorption. In the case of CO desorption is the exclusive photodepletion mechanism. PID efficiency decreases with increasing CO coverage suggesting PID hindrance by interactions among the desorbing CO molecules leading to re-adsorption at higher coverage. The wavelength and fluence dependence measurements exclude the possibility of laser induced thermal desorption for both adsorbates. The proposed mechanism for this phenomenon is desorption induced by hot electron transfer from the substrate to the adsorbate. Enhanced lifetime of transient negative adsorbate due to stabilization by localized holes on PSi nanotips can explain the observed abnormally large PID efficiency on top of porous silicon.},
doi = {10.1063/1.4788959},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 4,
volume = 138,
place = {United States},
year = {2013},
month = {1}
}