Adsorption of CO, O2, and H2O on GaAs(100): Photoreflectance Studies

E. G. Seebauer

doi:10.1116/1.576136

Adsorption of CO, O₂, and H₂O on GaAs(100): Photoreflectance Studies

E. G. Seebauer

Chemical and Biomolecular Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

Adsorption of CO, 0₂, and H₂O on semi-insulating GaAs(l00) has been examined with photoreflectance (PR). This work represents the first use of PR for quantitative adsorption measurements on semiconductors. In PR, the laser-induced change in surface reflectance is monitored as a function of wavelength. The resulting spectra are sensitive to changes in both the surface potential and the nature of surface states. Results at the E₁(3.0 eV) and E₀(1.4 eV) transitions are complementary to each other. Sticking coefficients S were obtained from E₁data for these gases, and S at low coverage was found to increase in the order CO<_O2<H₂O. S decreases by at least four orders of magnitude for all the gases as saturation is approached. The results suggest that oxygen has two binding states that fill sequentially. Gas adsorption generally improves the communication between isolated surface states and the bulk.

Original language	English (US)
Pages (from-to)	3279-3286
Number of pages	8
Journal	Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume	7
Issue number	6
DOIs	https://doi.org/10.1116/1.576136
State	Published - Nov 1989

ASJC Scopus subject areas

Condensed Matter Physics
Surfaces and Interfaces
Surfaces, Coatings and Films

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title = "Adsorption of CO, O2, and H2O on GaAs(100): Photoreflectance Studies",

abstract = "Adsorption of CO, 02, and H2O on semi-insulating GaAs(l00) has been examined with photoreflectance (PR). This work represents the first use of PR for quantitative adsorption measurements on semiconductors. In PR, the laser-induced change in surface reflectance is monitored as a function of wavelength. The resulting spectra are sensitive to changes in both the surface potential and the nature of surface states. Results at the E1(3.0 eV) and E0(1.4 eV) transitions are complementary to each other. Sticking coefficients S were obtained from E1data for these gases, and S at low coverage was found to increase in the order CO<O22O. S decreases by at least four orders of magnitude for all the gases as saturation is approached. The results suggest that oxygen has two binding states that fill sequentially. Gas adsorption generally improves the communication between isolated surface states and the bulk.",

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year = "1989",

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