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Composition and structure of the native Si oxide by high depth resolution medium energy ion scattering
A5 Surface Science 241 (1991) 91-102 North-Holland
91
Composition and structure of the native Si oxide by high depth resolution medium energy ion scattering Amir H. AI-Bayati, Kevin G. Orrman-Rossiter, J.A. van den Berg and D.G. Armour Department of Electronic and Electrical Engineering, University of Salfora~ Sal/ord M5 4WT, UK Received 7 June 1990; accepted for publication 29 August 1990 The structure and composition of the native Si oxide were studied using high depth resolution medium energy ion scattering (MEIS) spectrometry. The analysis revealed that the oxide is an amorphous material of thickness 20 /~. The results showed qualitatively that the interface between the oxide and the underlying structure consists of layers of Si atoms displaced from their normal lattice sites. The composition of the native Si oxide varies with depth. The region near the surface is more highly oxidized than that near the interface. However, based on the assumption that there are two nonregistered Si layers in the interface, the results showed that the oxide consists of a layer of stoichiometric SiO2 of thickness - 7 A and a layer of suboxide (SiOx, x < 2) of thickness
-6A.
Surface Science 241 (1991) 103-110 North-Holland
103
Sodium adsorption on a Si(001)-(2 × 1) surface M. Tikhov, G. Boishin and L. Surnev Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1040, Bulgaria Received 31 May 1990; accepted for publication 20 August 1990 The adsorption of Na on a Si(001)-(2 x 1) surface has been studied by means of AES, LEED, EELS, Temperature Programmed Desorption (TPD), and work function (AO) measurements. Four peaks are observed in the Na TPD spectra. The lowest temperature peak corresponds to a multilayer Na structure. The observed weak coverage dependence of the Na desorption energy suggests a predominantly covalent character of the Na-Si bonding. Our TPD data show that with Na in the first layer (0Na = 0.68), no metallization of the Na overlayer takes place. The AES, LEED, EELS and Ag, data give strong evidence of 3D clustering (Stranski-Krastanov growth mode), which at 300 K occurs for 0Na > 0.5.
Surface Science 241 (1991) 111-123 North-Holland
111
Adsorption of I on Si(111) and Si(110) surfaces E.G. Michel ~, Th. Pauly, V. Etel~niemi and G. Materlik Hamburger Synchrotronstrahlungslabor HAS YLAB at Deutsches Elektronen-Synchrotron DES Y, Notkestrasse 85, W-2000 Hamburg 52, Germany Received 5 June 1990; accepted for publication 27 August 1990 The adsorption of I on Si(lll)7 x 7 and Si(ll0)"16 x 2" reconstructed surfaces has been investigated by using X-ray standing-wave fields. The (ll 1) and (220) Fourier components of the I distribution function were measured for each surface, which allowed a precise determination of the adsorption site. In the case of Si(111)7 x 7, the reconstruction of the surface is released upon I adsorption, and the faulting of the 7 x 7 unit cell disappears in the regions where adsorption takes place. A position on top of the dangling bonds of the I-induced 1 × 1 surface is observed. In the Si(110)"16 x 2" case, I adsorption also induces a 1 x 1 dereconstruction. The adsorption site is the hollow one along the atomic chains present at the bulk-terminated surface.
91
Composition and structure of the native Si oxide by high depth resolution medium energy ion scattering Amir H. AI-Bayati, Kevin G. Orrman-Rossiter, J.A. van den Berg and D.G. Armour Department of Electronic and Electrical Engineering, University of Salfora~ Sal/ord M5 4WT, UK Received 7 June 1990; accepted for publication 29 August 1990 The structure and composition of the native Si oxide were studied using high depth resolution medium energy ion scattering (MEIS) spectrometry. The analysis revealed that the oxide is an amorphous material of thickness 20 /~. The results showed qualitatively that the interface between the oxide and the underlying structure consists of layers of Si atoms displaced from their normal lattice sites. The composition of the native Si oxide varies with depth. The region near the surface is more highly oxidized than that near the interface. However, based on the assumption that there are two nonregistered Si layers in the interface, the results showed that the oxide consists of a layer of stoichiometric SiO2 of thickness - 7 A and a layer of suboxide (SiOx, x < 2) of thickness
-6A.
Surface Science 241 (1991) 103-110 North-Holland
103
Sodium adsorption on a Si(001)-(2 × 1) surface M. Tikhov, G. Boishin and L. Surnev Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1040, Bulgaria Received 31 May 1990; accepted for publication 20 August 1990 The adsorption of Na on a Si(001)-(2 x 1) surface has been studied by means of AES, LEED, EELS, Temperature Programmed Desorption (TPD), and work function (AO) measurements. Four peaks are observed in the Na TPD spectra. The lowest temperature peak corresponds to a multilayer Na structure. The observed weak coverage dependence of the Na desorption energy suggests a predominantly covalent character of the Na-Si bonding. Our TPD data show that with Na in the first layer (0Na = 0.68), no metallization of the Na overlayer takes place. The AES, LEED, EELS and Ag, data give strong evidence of 3D clustering (Stranski-Krastanov growth mode), which at 300 K occurs for 0Na > 0.5.
Surface Science 241 (1991) 111-123 North-Holland
111
Adsorption of I on Si(111) and Si(110) surfaces E.G. Michel ~, Th. Pauly, V. Etel~niemi and G. Materlik Hamburger Synchrotronstrahlungslabor HAS YLAB at Deutsches Elektronen-Synchrotron DES Y, Notkestrasse 85, W-2000 Hamburg 52, Germany Received 5 June 1990; accepted for publication 27 August 1990 The adsorption of I on Si(lll)7 x 7 and Si(ll0)"16 x 2" reconstructed surfaces has been investigated by using X-ray standing-wave fields. The (ll 1) and (220) Fourier components of the I distribution function were measured for each surface, which allowed a precise determination of the adsorption site. In the case of Si(111)7 x 7, the reconstruction of the surface is released upon I adsorption, and the faulting of the 7 x 7 unit cell disappears in the regions where adsorption takes place. A position on top of the dangling bonds of the I-induced 1 × 1 surface is observed. In the Si(110)"16 x 2" case, I adsorption also induces a 1 x 1 dereconstruction. The adsorption site is the hollow one along the atomic chains present at the bulk-terminated surface.