GaAs{001}(2×4) surface-structure studies with shadow-cone-enhanced secondary-ion mass spectrometry

Xu, Can; Caffey, K. P.; Burnham, J. S.; Goss, S. H.; Garrison, Barbara J.; Winograd, Nicholas

doi:10.1103/physrevb.45.6776

Cited by 23 publications

(9 citation statements)

References 44 publications

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“…6. For the clean surface, 16 the major peak at ⌰ i ϭ70.1°arises from a Ga-Ga interaction in the second layer and corresponds with the bulk spacing of 4.00Ϯ0.10 Å. The shoulder at ⌰ i ϭ63.0°is associated with the first-layer As-As interaction and corresponds to a spacing of 2.73Ϯ0.10 Å, as reported previously.…”

Section: Resultssupporting

confidence: 81%

“…The experiments were performed in an ultrahigh vacuum ͑UHV͒ complex consisting of a Riber 2300 molecular-beam epitaxy ͑MBE͒ system and a surface analysis chamber equipped with low-energy electron diffraction ͑LEED͒ and angle-resolved SIMS. 16,25 The GaAs͕001͖ wafers were spin etched in a 10:1:1 solution of H 2 O:H 2 O 2 :NH 4 OH for 20 s rinsed in distilled water, and bonded to a Mo block with In before insertion into the vacuum system. The native oxides were removed in vacuum by heating to 900 K under As 4 flux.…”

Section: Methodsmentioning

confidence: 99%

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Submonolayer structure of an abrupt Al/GaAs{001}-(2×4) interface

Burnham

Sanders

et al. 1996

Phys. Rev. B

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The structure of As-terminated Al/GaAs͕001͖-(2ϫ4) has been determined in atomic detail using angleresolved secondary-ion-mass spectrometry. We find an abrupt interface is formed at room temperature by deposition of 0.3 ML of Al onto GaAs͕001͖-(2ϫ4) prepared in situ by molecular-beam epitaxy. The Al atoms are found to adsorb in the troughs between two As 2 dimers, in ordered sites 0.79Ϯ0.10 Å above the surface plane. These dimers maintain their 2.73-Å spacing after Al deposition. The structure is determined from angular distributions of Al ϩ and Ga ϩ ions desorbed by keV ions and computer simulations of the ionbombardment event.

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Section: Resultssupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Submonolayer structure of an abrupt Al/GaAs{001}-(2×4) interface

Burnham

Sanders

et al. 1996

Phys. Rev. B

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“…This shortening is attributed to the higher coordination about the arsenic atom and the addition of more s character to the molecular orbitals. 36,37 The mixing of s and p atomic orbitals on the fourfold-coordinated As atom is also evident in the As 1 -H 3 bond length of 1.536 Å. These results may be contrasted to the arsenic monohydrogen bonds on clusters 2 and 3, where a lone pair of electrons remains in the dangling bond.…”

Section: Resultsmentioning

confidence: 99%

Ab initiocluster calculations of hydrogenated GaAs(001) surfaces

Hicks

2000

Phys. Rev. B

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Hydrogen adsorption on the ͑2ϫ4͒ and ͑4ϫ2͒ reconstructions of gallium arsenide ͑001͒ has been studied by internal reflectance infrared spectroscopy and ab initio cluster calculations with density-functional theory. The calculations are made on Ga 5 As 4 H 11,13 , Ga 4 As 5 H 11,13 , and Ga 7 As 8 H 19 clusters, which model the arsenic-and gallium-dimer termination of the semiconductor surface. Excellent agreement has been achieved between the vibrational frequencies predicted by the theory and those observed in experiments. On the ͑2ϫ4͒, hydrogen adsorbs on arsenic dimers to form isolated and coupled arsenic-monohydrogen bonds, and arsenic-dihydrogen bonds. Conversely, on the ͑4ϫ2͒, hydrogen adsorbs on gallium dimers to form terminal and bridged gallium hydrides. The latter species occur in isolated or coupled structures involving two or three Ga atoms.

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“…LT-GaAs has various GaAs (001) phases where the (2x4) surface reconstruction is noted to be prevalent. [23][24][25][26][27][28][29][30][31][32] Specifically, the β2(2x4) corresponding to (2x4) structure with two missing As dimers at the top and one missing Ga dimer in the second top layer, 23,33 is found to be energetically more favorable over various (2x4) reconstruction for a wide range of arsenic chemical potential. [33][34][35][36][37] Our calculations for β2(2x4) give a formation energy value of 3.39 eV less than the formation energy of β(2x4) phase (i.e.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of structural, electronic, and optical properties of surface defects in GaAs(001) - β2(2x4)

et al. 2018

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We performed first-principles calculations based on density functional theory (DFT) to investigate the role of point defects in the structural, electronic, and optical properties of the GaAs(001)- β2(2x4). In terms of structural properties, AsGa is the most stable defect structure, consistent with experiments. With respect to the electronic structure, band structures revealed the existence of sub-band and midgap states for all defects. The induced sub-bands and midgap states originated from the redistributions of charges towards these defects and neighboring atoms. The presence of these point defects introduced deep energy levels characteristic of EB3 (0.97 eV), EL4 (0.52 eV), and EL2 (0.82 eV) for AsGa, GaAs, GaV, respectively. The optical properties are found to be strongly related to these induced gap states. The calculated onset values in the absorption spectra, corresponding to the energy gaps, confirmed the absorption below the known bulk band gap of 1.43 eV. These support the possible two-step photoabsorption mediated by midgap states as observed in experiments.

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GaAs{001}(2×4) surface-structure studies with shadow-cone-enhanced secondary-ion mass spectrometry

Cited by 23 publications

References 44 publications

Submonolayer structure of an abrupt Al/GaAs{001}-(2×4) interface

Submonolayer structure of an abrupt Al/GaAs{001}-(2×4) interface

Ab initiocluster calculations of hydrogenated GaAs(001) surfaces

First-principles study of structural, electronic, and optical properties of surface defects in GaAs(001) - β2(2x4)

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