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

Itoh, Makoto; Ohno, Takahisa

doi:10.1103/physrevb.62.7219

Cited by 8 publications

(5 citation statements)

References 64 publications

(85 reference statements)

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“…The feature at 265 cm −1 and the very weak feature approximately at 277 cm −1 in the experimental spectra (figure 2) can be a result of the presence of large GaAs islands with the average thickness 1 ML and more. The possibility of the presence of GaAs islands with the filled trenches was shown by Itoh and Ohno [15,16]. The calculated Raman spectra of the GaAs layers grown on the (001)-(2 × 4) reconstructed AlAs surface with the thickness from 1 to 1.5 ML are presented in figure 5.…”

Section: Study Of Gaas Islands Formed On a (001)-(2 × 4) Alas Interfacementioning

confidence: 87%

Interface reconstruction in GaAs/AlAs ultrathin superlattices grown on (311) and (001) surfaces

Efremov

Володин

Sachkov³

et al. 2001

Nanotechnology

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Phonon spectra of GaAs/AlAs superlattices (SLs) grown on (311)A, B and (001) surfaces were studied using Raman spectroscopy. The thickness of GaAs layers were varied from 1 to 10 monolayers (MLs); the thickness of AlAs barriers were 8 ML in the (311) direction. Different polarization geometries of Raman scattering were applied to study LO and TO modes. The splitting of TOx (atoms displace in the direction [011̄] perpendicular to the facets on the (311)A surface) and TOy (atoms displace in the [2̄33] direction parallel to the facets) modes was observed for (311)A SLs. In the case of (311)B SLs no splitting was observed. The phonon anisotropy of (311)A SLs may be indirect evidence of anisotropic structure of quantum objects formed on the (311)A GaAs surface. In the Raman spectra of the SL containing GaAs submonolayers (SML) grown on a (2×4) reconstructed (100) surface, Raman peaks corresponding to additional lateral confinement of LO phonons were observed. The calculations of Raman spectra were carried out using the Born-von-Karman model (taking into account Coulomb interaction in the rigid-ion model) and the Wolkenstein bond polarizability model. According to the calculations, the interface structure strongly influences the Raman spectra of GaAs/AlAs heterostructures containing GaAs SML.

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Section: Study Of Gaas Islands Formed On a (001)-(2 × 4) Alas Interfacementioning

confidence: 87%

Interface reconstruction in GaAs/AlAs ultrathin superlattices grown on (311) and (001) surfaces

Efremov

Володин

Sachkov³

et al. 2001

Nanotechnology

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“…In contrast to this, the B1a step edge enjoys its stability when it is straight in the ͓110͔ direction, and it is this difference that causes both sides to grow differently from each other. To confirm this, we carry out the growth simulations by choosing the same growth conditions as before, 8,9,[15][16][17] i.e., f Ga ϭ0.1 ML/s, f As 2 ϭ0.4 ML/s, and Tϭ580°C. By so doing, one can clarify the influence of atomic steps on the growth morphology by comparing the current results with the previous ones.…”

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confidence: 89%

“…9, 15 We have also reproduced the principal features of the temporal evolution of a specular intensity of RHEED by calculating the density of double As dimers characterizing the ␤2(2ϫ4) structure. 16 Recently, we also reported our results of the kMC simulations on the step-flow growth modes of both the A and B steps, which are parallel to the ͓1 10͔ direction and to the ͓110͔ direction, respectively. 17 By these simulations, it has been found that the kinetics of both species play crucial roles for the growth anisotropy between A and B steps due to the fact that there is a difference in the number of Ga adatoms needed for a terrace edge to accommodate an As dimer so as to enable the growth.…”

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confidence: 93%

“…More precisely, the splitting of a wide As dimer row into a pair of double As dimer rows commonly occurs at a terrace edge as the rate-limiting process to adopt the ␤2(2ϫ4) structure. 8,9,[15][16][17] Therefore, these fluctuations are inevitable for the growth of a GaAs(001)-␤2(2ϫ4) surface irrespective of whether it is singular or vicinal. Even in the presence of these fluctuations, the mean direction of the terrace edges along this strip remains parallel to the ͓100͔ direction.…”

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confidence: 99%

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Kinetic Monte Carlo study of step asymmetry and stable step orientations on GaAs(001)

Itoh

2001

Phys. Rev. B

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Step morphology in the homoepitaxial growth of a GaAs(001)-␤2(2ϫ4) surface is studied by kinetic Monte Carlo simulations. The growth simulations revealed that one of the two types of B steps we examined grows by keeping the mean step direction parallel to ͓110͔ with punctuated protrusions of As dimer rows along the ͓1 10͔ direction, whereas the other type tends to have a step orientation parallel to one of the two orthogonal ͗010͘ directions. These results can be examined by observing vicinal surfaces of GaAs͑001͒ with scanning tunneling microscopy.The combined use of epitaxial growth and reflection highenergy electron diffraction ͑RHEED͒ is a popular technique to fabricate heterostructures 1 and to integrate optoelectronic devices. To accomplish these tasks, it is necessary to control growth with the accuracy of an atomic layer thickness so as to realize the interface abruptness. Accordingly, ab initio density-functional calculations have been used to explore the atomic and electronic structures of various surface reconstructions with the aim at revealing their roles in growth. The prototypical example of this kind of study is the finding of the bistability of Si͑001͒ between an S A step and an S B step, as first pointed out by Chadi with tight-binding total-energy calculations, 2 and later confirmed by scanning tunneling microscope ͑STM͒ observations. 3 Here, we will point out that a similar bistability also exists on a GaAs(001)-␤2(2ϫ4) reconstructed surface, i.e., on the best-studied III-V compound semiconductor surface. 4,5 Since many optoelectronic devices are made of III-V semiconductors, this phenomenon may be used to control growth and, hence, to improve the quality and performance of such devices. However, the best method to study this is obviously not to perform ab initio density-functional energyminimization calculations as it has the limitations on the system size and the time scales to simulate growth phenomena. Instead, it is practically more suitable to carry out kinetic Monte Carlo ͑kMC͒ simulations 6 to fulfill this task.The surface reconstruction of our concern is the ␤2(2 ϫ4) structure, which appears during molecular-beam epitaxial growth at TӍ580°C when the arsenic pressure is kept sufficiently high. 7 For convenience, the ␤2(2ϫ4) reconstruction is depicted in Fig. 1, where the dark and bright disks denote As and Ga atoms, respectively, and their radii decrease according to their depths. The shaded areas in Figs. 1͑a͒ and 1͑b͒ indicate the sites to which an additional As dimer may stick and initiate the growth of this structure in the ͓110͔ direction and the ͓1 10͔ direction, respectively.To investigate the evolution of the surface morphology on GaAs͑001͒, we have carried out kMC simulations based on the two-species growth model, in which both Ga atoms and As 2 molecules are deposited simultaneously onto a ␤2(2 ϫ4)-reconstructed surface at Tϭ580°C. 8,9 The interaction diagrams of the As part used in the model are seen in Figs. 2͑a͒-2͑e͒. 10 Among them, the interactions depicted in Figs. 2͑d͒ ...

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“…9 Since the double As dimers characterize the ␤2͑2 ϫ 4͒ reconstruction, our result results from the fact that the time dependent part of a RHEED intensity comprises a minor portion of the total intensity, so that to the first order approximation, the time evolution of a specular RHEED intensity is proportional to the summation of the time evolutions of the relevant surface features. 9 Since the double As dimers characterize the ␤2͑2 ϫ 4͒ reconstruction, our result results from the fact that the time dependent part of a RHEED intensity comprises a minor portion of the total intensity, so that to the first order approximation, the time evolution of a specular RHEED intensity is proportional to the summation of the time evolutions of the relevant surface features.…”

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confidence: 95%

Probing the submonolayer morphology change in epitaxial growth: A simulation study

Itoh

Ohno

2007

Applied Physics Letters

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

Cited by 8 publications

References 64 publications

Interface reconstruction in GaAs/AlAs ultrathin superlattices grown on (311) and (001) surfaces

Interface reconstruction in GaAs/AlAs ultrathin superlattices grown on (311) and (001) surfaces

Kinetic Monte Carlo study of step asymmetry and stable step orientations on GaAs(001)

Probing the submonolayer morphology change in epitaxial growth: A simulation study

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