Atomic structure and electronic properties of the In/Si(111)2×2 surface (original) (raw)
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Surface Science, 1997
Low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunnelling microscopy (STM) have been used to study the evolution of the surface structure upon room temperature deposition of In onto In-predeposited Si(111)√3 × √3-In surface. The sequential formation of the Si(111)2 × 2 and Si(111)√7 × √3 surface phases has been detected and coverage ranges of their existence have been determined. STM observations have revealed that the Si(111)2 × 2-In phase has a honeycomb-like atomic structure with depressions in T4 positions. The structural model built of In trimers has been proposed. The “low-temperature” Si(111)√7 × √3-In phase shows up in STM images as parallel rows of protrusions and its structure has been found to differ from the structure of the known “high-temperature” Si(111)√7 × √3-In phases. The inheritance of the defects at the structural transition from √3 × √3 structure to 2 × 2 structure has been discussed.
Indium Growth on Reconstructed Si(111)√3 × √3 and 4 × 1 In Surfaces
The Journal of Physical Chemistry C, 2010
The morphology and growth mechanism of nanostructured metals on semiconducting substrates determine crucially the electronic and physicochemical properties of these adsorption systems. In some cases, these properties are affected by modification of the interfacial geometry, induced by the metal adsorbate on the semiconducting substrate. Thus, in this work we investigate indium growth on the Si(111) 3 × 3 and Si(111)4 × 1 surfaces reconstructed by indium. The basic motivation of this study is to reveal how reconstruction of the silicon surface affects the growth mode and electronic properties of the indium overlayer. Therefore, the In/Si interface was mainly studied by Si 2p and In 4d photoemission spectra as well as by valence band measurements using synchrotron radiation. In addition, low-energy electron diffraction, Auger electron spectroscopy, thermal desorption spectroscopy, and electron energy loss spectroscopy were used to reveal the structure and adsorption states of the indium adsorbate on the reconstructed silicon substrates. The results indicate that the initial In-Si surface symmetry affects the growth mechanism of the indium overlayer. In particular, the Stransky-Krastanov mode holds for indium adsorption on the clean Si(111)7 × 7 and Si(111) 3 × 3 In-reconstructed surface. On the other hand, indium develops on the Si(111)4 × 1 In surface according to the Volmer-Weber mechanism. The adsorbate approaches the metallic phase as the coverage approximates the monolayer irrespective of the substrate symmetry.
Formation of In-Induced Superstructural Phases on Si(111)7 × 7 Reconstructed Surface
Journal of Nanoscience and Nanotechnology, 2009
Adsorption of Group III metal In nanostructures on Si surfaces is an exciting field that integrates the exotic electronic properties of the nano-phase and the p-doping abilities of In. We present here the kinetics of growth of In on (7 × 7) reconstructed Si(111) surface by experiments done in ultra high vacuum in the submonolayer regime, probed in-situ by surface sensitive techniques. Indium is observed to grow in the layer by layer mode. The study reveals adsorption behavior dictated by layer-dependent mobilities of In atoms that causes initial island formation that later wet the surface. However the desorption studies manifest the initial agglormeration of top layer atoms, which at higher temperatures overcome step-edge barriers and consequently two-dimensional layering of three-dimensional islands before sublimation occurs. Thus the study reveals the kinetic details of the anamolour behavior of the In/Si interface formation and desorption that can enable the tailor making of several nano-phases and structures of characteristic properties.
The growth of indium on the H-terminated Si(111)1 × 1 surface
Surface Science, 1997
The growth morphology and the chemical interactions of thin In layers on an H-terminated Si(111)1 × 1 surface, prepared by a wet chemical procedure, have been investigated by scanning tunneling microscopy (STM) and synchrotron radiation based photoemission. The interactions between the In overlayer and the H-Si(1 x 1) surface are weak as evidenced by valence band and core level photoemission spectra. As on the clean Si(111)7 × 7 surface an island growth mode of In is observed on the H-Si(1 x 1) surface, but the island structures display significant differences in shape and growth behaviour between the two surfaces, indicating a modified In growth kinetics mediated by the H adlayer. This surfactant-type role of H is discussed. Annealing of the room temperature deposited In layers results in remarkable coverage-dependent morphology changes which signal the predominance of kinetic effects in the room temperature growth. For higher In coverages (> 25 monolayers) well-ordered single crystalline In islands are formed at room temperature as indicated by atomically resolved STM images and angle resolved photoemission measurements.
Surface Science, 1996
Indium adsorption and desorption processes on Si(111) surfaces were observed in situ by UHV high-temperature STM. By the deposition of In on the Si(lll)7 X 7 surfaces at 380°C, the surface structure changed successively to f3-x 73-, 3~ × 3~ and 4 × 1. The number densities of silicon atoms in the restructuring layers for the v~ X 7~-, ~ × 3~-, and 4 x 1 structures were evaluated to be about 0, 1 and 2 ML, respectively. High-resolution STM images were also taken after the deposition.
Physical Review B, 2009
Structural properties of monatomic indium chains on Si͑111͒5 ϫ 2-Au surface are investigated by scanning tunneling microscopy ͑STM͒ and first-principles density functional calculations ͑DFT͒. The STM topography data show that submonolayer coverage of indium leads to a well-ordered chain structure with the same periodicity as the Si adatoms form on Si͑111͒5 ϫ 2-Au surface. Bias-dependent STM topography and spectroscopy reveal two different mechanisms of In-atoms adsorption on the surface: bonding to Si adatoms and substitution for Si atoms in the adatom positions. Those mechanisms are further corroborated by DFT calculations. The obtained structural model of In-modified Si͑111͒5 ϫ 2-Au surface remains in good agreement with the experimental data.
Surface structure of Si(111)-(8×2)–In determined by reflection high-energy positron diffraction
Surface Science, 2008
By using reflection high-energy positron diffraction (RHEPD) and first-principles calculations, we investigated an In/Si(1 1 1) surface on which the quasi-one-dimensional In atomic chains that exhibit the metal-insulator transition were formed. From the analyses of rocking curves, we found the transformation of the zigzag chain structure of In atomic chains to hexagon structures below 130 K along with the phase transition from the 4 Â 1 to the 8 Â 2 periodicities. The band structure calculated with the optimum hexagon structure displays the gap opening of 60 meV, which indicates the semiconducting character. This confirms the recent theoretical prediction that the hexagon structure is energetically favored at low temperatures [C.
Metal–insulator transition in the In/Si(1 1 1) surface
Surface Science, 2006
The metal-insulator transition observed in the In/Si(111)-4×1 reconstruction is studied by means of ab initio calculations of a simplified model of the surface. Different surface bands are identified and classified according to their origin and their response to several structural distortions. We support the, recently proposed [New J. of Phys. 7 (2005) 100], combination of a shear and a Peierls distortions as the origin of the metal-insulator transition. Our results also seem to favor an electronic driving force for the transition.