Reflectance anisotropy of the GaAs(001) (2×4) surface:<i>Ab initio</i>calculations

Morris, Stephen; Bass, Julian M.; Matthai, Clarence Cherian

doi:10.1103/physrevb.52.16739

Cited by 24 publications

(21 citation statements)

References 24 publications

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“…Most of these adatoms are migrating in trenches during growth by locally taking an ␣(2ϫ4) structure. Therefore, this is in rough agreement with Morris et al's theoretical analyses 30 of the reflection anisotropy spectroscopy ͑RAS͒ Fig. 10, respectively.…”

Section: Growth Simulationsupporting

confidence: 89%

Relevance of surface reconstruction to specular RHEED intensity on GaAs(001)

Itoh¹,

Ohno²

2000

Phys. Rev. B

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By carrying out atomic-scale growth simulations of a GaAs(001)-␤2(2ϫ4) surface, we find that the density of double As dimers evolves synchronously with the observed specular reflection high-energy electrondiffraction ͑RHEED͒ intensities in growth and after its interruption. At the same time, we find that a step density does not even oscillate during growth. We further show that the structural transition of initial growing islands from a non-͑2ϫ4͒ structure to the ␤2(2ϫ4) structure found previously can be detected in situ by specular RHEED observation. The fast and slow recovery processes after growth interruption are identified, respectively, as the incorporation of Ga adatoms to surface structures, and the phase ordering of various domains consisting of the ␤2(2ϫ4) structure. We also relate these results to a specular RHEED intensity with the help of ab initio calculations.

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Section: Growth Simulationsupporting

confidence: 89%

Relevance of surface reconstruction to specular RHEED intensity on GaAs(001)

Itoh¹,

Ohno²

2000

Phys. Rev. B

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“…Other calculations model the effect of the surface termination of the bulk electronic wave functions [13] or the piezo-optical effect [14,15]. Previous ab initio calculations of the GaAs surface optical properties [16][17][18] were for computational reasons restricted to rather thin slabs and used a relatively small number of basis functions. They were thus severely limited in their reliability.…”

Section: Introductionmentioning

confidence: 99%

GaAs(001): Surface Structure and Optical Properties

Schmidt

Bechstedt

Fleischer

et al. 2001

phys. stat. sol. (a)

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The optical anisotropy of differently reconstructed GaAs(001) surfaces has been analysed both theoretically and experimentally. The atomic structures and RAS spectra are calculated from first principles for the As-rich c(4 Â 4) and b2(2 Â 4) as well as for the stoichiometric a2(2Â4) and the Ga-rich z(4 Â 2) surface phases. These results are compared with spectra recorded at low temperature (40 K). We find good agreement between the calculated and measured data, in particular for the As-rich surface phases. In marked contrast to earlier calculations we find the peak near the E 1 critical point energy, characteristic of the b2(2 Â 4) surface, to originate from electronic transitions in bulk layers. The experimental data for the Ga-rich (4 Â 2) surface phase are less well reproduced, possibly due to surface defects or structural deviations from the z(4 Â 2) model for the surface geometry.

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“…[5][6][7] While the line shapes of the c(4ϫ4), (2 ϫ4)/c(2ϫ8), and (4ϫ2)/c(8ϫ2) surfaces have been correlated with electron diffraction patterns ͓reflection highenergy electron diffraction and low-energy electron diffraction͔, 1 the physical origin of the reflectance anisotropy has not been conclusively determined. Uncertainty remains as to whether the reflectance anisotropy is a result of bulksurface transitions, [8][9][10][11][12] or by transitions among the molecular orbitals of the surface dimers. 13,14 Early efforts to account for the reflectance anisotropy involved the calculation of the surface dielectric function of simplified GaAs surfaces.…”

Section: Introductionmentioning

confidence: 99%

Reflectance-difference spectroscopy of mixed arsenic-rich phases of gallium arsenide (001)

Begarney

et al. 2000

Phys. Rev. B

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The relationship between the reflectance difference spectra and the atomic structure of arsenic-rich reconstructions of GaAs͑001͒ has been investigated. Scanning tunneling micrographs reveal that a roughening process occurs as the surface structure changes with decreasing arsenic coverage from 1.75 to 0.75 monolayers ͑ML͒. At 1.65 ML As, small pits, one bilayer in depth and having the same c(4ϫ4) reconstruction as the top layer, form in the terraces. At the same time, gallium atoms are liberated to the surface, disrupting the c(4 ϫ4) ordering. At about 1.4 ML As, (2ϫ4) domains nucleate and grow on top of the c(4ϫ4). Further desorption of arsenic causes the underlying layer to gradually decompose into a metastable (2ϫn) phase (n ϭ2, 3, or 4͒, and finally into the (2ϫ4). In the reflectance difference spectra, negative peaks at 2.25 and 2.8 eV correlate with the c(4ϫ4)-type arsenic dimers. However, the intensity of the latter feature strongly depends on the presence of adsorbates, such as alkyl groups and gallium adatoms. By contrast, the intensity of the positive peak at 2.9 eV is directly proportional to the density of (2ϫ4)-type dimers.

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Reflectance anisotropy of the GaAs(001) (2×4) surface:Ab initiocalculations

Cited by 24 publications

References 24 publications

Relevance of surface reconstruction to specular RHEED intensity on GaAs(001)

Relevance of surface reconstruction to specular RHEED intensity on GaAs(001)

GaAs(001): Surface Structure and Optical Properties

Reflectance-difference spectroscopy of mixed arsenic-rich phases of gallium arsenide (001)

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