Effect of surface intermixing on the morphology of Sb-terminated Ge(100) surfaces

Chan, L.; Altman, Eric I.

doi:10.1103/physrevb.63.195309

Cited by 18 publications

(8 citation statements)

References 47 publications

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“…[10][11][12] Briefly, experiments were performed using an ultrahigh-vacuum system equipped with an energy analyzer for Auger electron spectroscopy ͑AES͒, an ion gun for sputtering, low-energy electron-diffraction ͑LEED͒ optics, resistively heated evaporation sources, a quartz crystal deposition rate controller, and a scanning tunneling microscope. 13 The Ge samples were nominally undoped with a resistivity of 50-60 ⍀ cm.…”

Section: Methodsmentioning

confidence: 99%

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Chan

Altman

2002

Phys. Rev. B

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Silver growth on Ge͑100͒ between 330 and 570 K was studied using scanning tunneling microscopy. At 330 K, three-dimensional ͑3D͒ clusters along with two types of two-dimensional ͑2D͒ islands were observed: one elongated perpendicular to the substrate dimer rows, the other parallel to the dimer rows. The spacing and registry with the substrate of the former could be explained by Ag adatoms attaching across the substrate dimer bond, while the latter could be attributed to Ag ad-dimers. Annealing caused the larger 3D clusters to grow at the expense of the smaller 3D clusters and 2D islands; at 470 K the 2D islands were completely eliminated. Low-energy electron diffraction indicated that the 3D clusters were oriented with their ͑110͒ planes parallel to the surface. After annealing, the 3D clusters became elongated parallel to the Ge dimer rows indicating that the Ag͓1 10͔ direction aligns parallel to the Ge 1ϫ direction. Although this suggested that the 3D clusters were lower in energy, Ag growth at 470 K led to two types of 2D islands along with pitting of the Ge surface; the pitting was taken as an indication that the islands were intermixed. Images of the islands revealed 2ϫ3 and 3ϫ2 periodicities. Images of the 3ϫ2 structure showed a single maximum per unit cell, while images of domain boundaries showed that the 3ϫ2 structure changed the outermost Ge layer. A model based on Ag-Ge mixed ad-dimers and Ag substitution into the Ge surface can explain these features. The 2ϫ3 and 3ϫ2 structures could only be seen after Ag deposition at ϳ470 K; both annealing films deposited at lower temperatures and higher growth temperatures created only 3D clusters. Thus formation of these intermixed structures was attributed to growth of metastable Ag-Ge nuclei at 470 K that were kinetically inhibited from forming at lower temperatures and whose lifetimes were too short to grow at higher temperatures.

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Section: Methodsmentioning

confidence: 99%

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Chan

Altman

2002

Phys. Rev. B

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“…4 also suggest that the conversions among S, S A , and AA are reversible when no external strain is present; it is in good agreement with the experimental observation. 5 When a compressive strain is applied to Ge͑001͒, the barrier for S to S A decreases significantly; at the same time, the energy of S A is also lowered. Meanwhile, the barrier from S A to AA is significantly increased and the energy of AA is raised ͓see Fig.…”

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confidence: 96%

“…These energetic results help explain that Sb 4 on Si͑001͒ tend to form AA type structure as a pair of dimers, [2][3][4]14 while Sb 4 on Ge͑001͒ favor to form S or S A type clusters. 5 The detailed structural information such as bond distances have been reported by Martínez-Guerra et al 13 and are omitted here.…”

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confidence: 97%

“…1 A typical example is the reaction of group-V elements ͑e.g., As, Sb, and Bi͒ with Si and Ge surfaces. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] For Sb 4 on Si͑001͒, the three-dimensional ͑3D͒ clusters can convert to flat tetramers that can then split into pairs of dimers. Scanning tunneling microscopy ͑STM͒ measurements 2-4 and density-functional theory ͑DFT͒ calculation 14 revealed a two-stage reaction process involving two distinct pathways, along and across the surface dimer row via a rhombus intermediate state.…”

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confidence: 99%

“…Similar but distinct reaction behavior is also observed for Sb 4 on Ge͑001͒ where STM measurements identified a pathway involving a twodimensional ͑2D͒ flat square intermediate state across the surface dimer row. 5 Such processes have attracted considerable attention because they play a key role in the epitaxial growth of Ge/Si heterostructures. [15][16][17][18] In this Brief Report, we present a comprehensive search on the dissociation energetics and kinetics of Sb 4 on Ge͑001͒ surface with biaxial strain using DFT calculations.…”

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Effect of strain on the energetics and kinetics of dissociation ofSb4on Ge(001)

et al. 2008

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A comprehensive search for the precursor dissociation of antimony tetramers on Ge͑001͒ with strain was carried out using first-principles calculations. In contrast to previous theoretical studies on Si͑001͒ ͓Phys. Rev. Lett. 97, 046103 ͑2006͔͒ and in agreement with recent experiments, we reveal a square intermediate anisotropy dissociation pathway across the surface dimer row, where the dissociation energetics and kinetics can be qualitatively altered by the strain and lead to divergent dissociation pathways and patterns with substratedimer-bond breaking due to the weak interactions between Ge-Ge and Sb-Ge bonds.It has long been known that molecular chemisorption on solid surfaces often involves intermediate precursor states and several competing dynamical processes such as dissociation, diffusion, and desorption. 1 A typical example is the reaction of group-V elements ͑e.g., As, Sb, and Bi͒ with Si and Ge surfaces. 2-18 For Sb 4 on Si͑001͒, the three-dimensional ͑3D͒ clusters can convert to flat tetramers that can then split into pairs of dimers. Scanning tunneling microscopy ͑STM͒ measurements 2-4 and density-functional theory ͑DFT͒ calculation 14 revealed a two-stage reaction process involving two distinct pathways, along and across the surface dimer row via a rhombus intermediate state. Similar but distinct reaction behavior is also observed for Sb 4 on Ge͑001͒ where STM measurements identified a pathway involving a twodimensional ͑2D͒ flat square intermediate state across the surface dimer row. 5 Such processes have attracted considerable attention because they play a key role in the epitaxial growth of Ge/Si heterostructures. [15][16][17][18] In this Brief Report, we present a comprehensive search on the dissociation energetics and kinetics of Sb 4 on Ge͑001͒ surface with biaxial strain using DFT calculations. They show sensitive dependence on the strain state of the substrate: in the absence of an external strain, Sb 4 dissociates via a square intermediate state with a bond-twisting assisted rigid rotation mechanism for the first-stage conversion and a substrate-dimer-bond-breaking assisted piecewise rotation dissociation pathway across the dimer row for the secondstage conversion. While with an applied strain, the energetics and kinetics can be qualitatively altered, leading to distinct reaction pathways and patterns due to the weak interactions between Ge-Ge and Sb-Ge bonds. For comparison, we also performed calculations for Sb 4 on Si͑001͒. In stark contrast to the case of Sb 4 on Ge͑001͒, the external strain has little effect on the dissociation behavior on Si͑001͒ due to the strong interactions between Sb-Si and Si-Si bonds.The reported calculations are carried out using VASP code 19 with ultrasoft pseudopotentials 20 and the generalized gradient approximation ͑GGA͒. 21 An energy cutoff of 200 eV for the plane-wave basis set is used. The supercell size is set to XYZ =16ϫ 32ϫ 35.72 Å 3 with ten layers of Ge in the Z direction and one layer of hydrogen to passivate the bottom Ge layer. The XY plane corr...

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Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE

Yurasov

Антонов

Дроздов

et al. 2018

Journal of Crystal Growth

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Effect of surface intermixing on the morphology of Sb-terminated Ge(100) surfaces

Cited by 18 publications

References 47 publications

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Effect of strain on the energetics and kinetics of dissociation ofSb4on Ge(001)

Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE

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Effect of surface intermixing on the morphology of Sb-terminated Ge(100) surfaces

Cited by 18 publications

References 47 publications

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Formation of metastable two-dimensional structures during Ag growth on Ge(100)

Effect of strain on the energetics and kinetics of dissociation ofSb4on Ge(001)

Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE

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Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE