- Email: [email protected]
Structural and electronic properties induced by hydrogen adsorption on the GaAs(110) surface
A108 Surface Science 244 (1991) 39-50 North-Holland
39
The surface oxidation of alpha-silicon carbide by O 2 from 300 to 1373 K James M. Powers and Gabor A. Somorjai Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA and Department of Chemistry, University of California, Berkeley, CA 94720, USA Received 25 June 1990; accepted for publication 28 September 1990 Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS) were used to investigate the oxidation of single crystal a-SiC over a wide temperature and O2 pressure range. In ultra-high vacuum, the surface composition of a-SiC (0001) as a function of temperature changes due to oxide formation and the sublimation of S i t and Si, yielding graphitic surface carbon. From 300 to 833 K, exposure of Ar* bombarded a-SiC to 10 - s Tort Oz results in a two-stage oxidation process which yields a submonolayer oxide. Highly disordered a-SiC surfaces were found to oxidize faster and more extensively than well-annealed, ordered surfaces. Exposure of the a-SiC(0001} surfaces to 1 arm O2 resulted in the production of S i t 2 overlayers, which were examined using XPS and Scanning AES (SAES). In these experiments the (0001) surface produced thicker S i t 2 overlayers than the (0001) surface. However, the difference in oxide thickness between the two {0001} surfaces was not as dramatic as previously reported and varied from sample to sample. Carbon was not detected in the surface S i t 2 layers formed between 973 and 1373 K, which suggested carbon was removed as CO and/or CO2 during the SiC oxidation process.
Surface Science 244 (1991) 51-57 North-Holland
51
Structural and electronic properties induced by hydrogen adsorption on the GaAs(ll0) surface A.F. Wright, C.Y. Fong Department of Physics, University of California, Davis, CA 95616, USA
and Inder P. Batra IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, USA Received 13 July 1990; accepted for publication 26 September 1990 The structural and electronic properties for hydrogen adsorbed on the GaAs(110) surface have been studied by the self-consistent pseudopotential method with a slab geometry and half and one monolayer coverages. The positions of the hydrogen atoms and the surface atoms for the stable configuration are given. The bonding nature is presented and the states at the Fermi energy are also determined.
58
Surface Science 244 (1991) 58-66 North-Holland
AES, LEELS and XPS studies on the interface formation between layered semiconductors GaSe and InSe N. Nakayama, T. Kuramachi, T. Tanbo, H. Ueba and C. Tatsuyama Department of Electronics, Faculty of Engineering, Toyama University, Gofuku, Toyama 930, Japan Received 25 January 1990; accepted for publication 15 October 1990 The interface formation at the initial stage of hetero-epitaxy of GaSe and lnSe, and InSe on GaSe has been studied b y means of AES (Auger electron spectroscopy), LEELS (low-energy electron loss spectroscopy) and XPS (X-ray photoemission spectroscopy). GaSe (InSe) was deposited onto the cleaved substrate by using a W filament. The growth mode was determined by mzasuring the decrease in the AES signal intensity from the substrate and the evolution of the LEELS spectrum upon deposition, which revealed
39
The surface oxidation of alpha-silicon carbide by O 2 from 300 to 1373 K James M. Powers and Gabor A. Somorjai Center for Advanced Materials, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA and Department of Chemistry, University of California, Berkeley, CA 94720, USA Received 25 June 1990; accepted for publication 28 September 1990 Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS) were used to investigate the oxidation of single crystal a-SiC over a wide temperature and O2 pressure range. In ultra-high vacuum, the surface composition of a-SiC (0001) as a function of temperature changes due to oxide formation and the sublimation of S i t and Si, yielding graphitic surface carbon. From 300 to 833 K, exposure of Ar* bombarded a-SiC to 10 - s Tort Oz results in a two-stage oxidation process which yields a submonolayer oxide. Highly disordered a-SiC surfaces were found to oxidize faster and more extensively than well-annealed, ordered surfaces. Exposure of the a-SiC(0001} surfaces to 1 arm O2 resulted in the production of S i t 2 overlayers, which were examined using XPS and Scanning AES (SAES). In these experiments the (0001) surface produced thicker S i t 2 overlayers than the (0001) surface. However, the difference in oxide thickness between the two {0001} surfaces was not as dramatic as previously reported and varied from sample to sample. Carbon was not detected in the surface S i t 2 layers formed between 973 and 1373 K, which suggested carbon was removed as CO and/or CO2 during the SiC oxidation process.
Surface Science 244 (1991) 51-57 North-Holland
51
Structural and electronic properties induced by hydrogen adsorption on the GaAs(ll0) surface A.F. Wright, C.Y. Fong Department of Physics, University of California, Davis, CA 95616, USA
and Inder P. Batra IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, USA Received 13 July 1990; accepted for publication 26 September 1990 The structural and electronic properties for hydrogen adsorbed on the GaAs(110) surface have been studied by the self-consistent pseudopotential method with a slab geometry and half and one monolayer coverages. The positions of the hydrogen atoms and the surface atoms for the stable configuration are given. The bonding nature is presented and the states at the Fermi energy are also determined.
58
Surface Science 244 (1991) 58-66 North-Holland
AES, LEELS and XPS studies on the interface formation between layered semiconductors GaSe and InSe N. Nakayama, T. Kuramachi, T. Tanbo, H. Ueba and C. Tatsuyama Department of Electronics, Faculty of Engineering, Toyama University, Gofuku, Toyama 930, Japan Received 25 January 1990; accepted for publication 15 October 1990 The interface formation at the initial stage of hetero-epitaxy of GaSe and lnSe, and InSe on GaSe has been studied b y means of AES (Auger electron spectroscopy), LEELS (low-energy electron loss spectroscopy) and XPS (X-ray photoemission spectroscopy). GaSe (InSe) was deposited onto the cleaved substrate by using a W filament. The growth mode was determined by mzasuring the decrease in the AES signal intensity from the substrate and the evolution of the LEELS spectrum upon deposition, which revealed