Surface-stress-induced order in SiGe alloy films

LeGoues, F. K.; Kesan, V. P.; Iyer, Subramanian S.; Tersoff, J.; Tromp, R. M.

doi:10.1103/physrevlett.64.2038

Cited by 158 publications

(75 citation statements)

References 14 publications

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“…Very high electron mobilities and the fractional quantum Hall effect have been observed in the strained Si layers grown between relaxed SiGe layers [7][8][9]. Ordering of the Si and Ge atoms within the alloy has been predicted [10], observed by various groups [3][4][5] and it is still subject of controversy [11]. Since the SiGe alloy system is compatible with the existing silicon microfabrication technology, it represents a challenging alternative to III-V semiconductor based device technology and recently, high speed commercial applications have started to emerge from SiGe based devices [12].…”

Section: Introductionmentioning

confidence: 92%

“…However, we believe that more detailed experiments, particularly those using scanning tunneling spectroscopy together with the STM, would eventually reveal a contrast between Si and Ge atoms. Further experiments are necessary to understand the mechanisms of ordering, segregation and composition fluctuations in Six_xGe x alloys which have been predicted [10] and observed by different methods on a coarse scale [3][4][5]11]. Different diffusion and sticking coefficients for Si and Ge atoms on the surface are expected to result in very interesting growth schemes and alloy atomic structures.…”

Section: Discussionmentioning

confidence: 99%

“…However, the strain is relaxed if the thickness of the grown layer exceeds the critical thickness which depends on the concentration. Growth of this technologically as well as scientifically important alloy has been extensively studied by various groups using different techniques [1][2][3][4][5]. This material system has attracted much attention for the potential opto-electronic applications [6].…”

Section: Introductionmentioning

confidence: 99%

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Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Oral

Ellialtioglu

1995

Surface Science

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We have studied the initial stages of strained SiGe alloy growth on the Si(001)-(2 × 1) surface by scanning tunneling microscopy. The Si0.36Ge0.64 alloy was grown on the silicon substrate at various coverages (0.13-3.6 ML) and at different temperatures (~ 310-470°C). The growth was one dimensional, preferring the direction perpendicular to the underlying silicon dimer rows at low coverages and low temperatures. Anti-phase boundaries were observed to lead multi-layer growth. Strong interaction between the overlayer and the substrate was found to buckle the substrate as well as SiGe dimers. Different growth mechanisms, island formation and step flow, were identified at low and high substrate temperatures. (2 X n) ordering of the strained overlayer was only observed at an intermediate growth temperature (~ 390°C).

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Section: Introductionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Oral

Ellialtioglu

1995

Surface Science

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“…The present work is motivated by recent experimental studies on spontaneous ordering of Si0.5Ge0.5 alloy [1][2][3][4][5][6][7]. The order takes the form of Si2/Ge2 superlattice oriented in {111} directions.…”

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confidence: 99%

Thermodynamic Stability of Two Rhombohedral Phases of Si_0.5Ge_0.5Alloy

Bogusławski

1991

Acta Phys. Pol. A

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Thermodynamic stability of two ordered phases, RS1 and RS2, of Si0.5Ge0.5 alloy is considered. Bulk and surface formation enthalpies are calculated using the model Tersoff's potential. RS2 structure is unstable, but its (001) ordered surface is stable against segregation. Properties of RS1 are just the opposite.PACS numbers: 61.55. Hg, 68.35.Md, 68.60.Dv The present work is motivated by recent experimental studies on spontaneous ordering of Si0.5Ge0.5 alloy [1][2][3][4][5][6][7]. The order takes the form of Si2/Ge2 superlattice oriented in {111} directions. This stucture has the rhombohedral symmetry, and may exist in two variants shown in Fig. 1. In the first one, denoted by RS1, the widely spaced (111) planes are occupied by the same type of atoms forming a sequence -Si≡ -G e -G e ≡ -S i -. . . , w h e r e t h e d a s h e s d e n o t e b o n d s b e t w e e n p l a n e s . I n the second RS2 variant the widely spaced (111) planes are occupied by unlike atoms, forming a sequence -Si ≡Si-Ge≡Ge-...Analysis by LeGoues et al. [4] has demonstrated that the phase that grows spontaneously is the RS2 structure. Upon annealing this phase disappears, and the alloy becomes random. However, in the case of Si/SiGe or Si/Ge superlattices, a long annealing may lead to a reversible appearance of the long-range order at the interfaces, which now takes the form of the RS1 structure [7].Here, we present an attempt to understand this behavior, and we analyze thermodynamic stability at T = 0 of Si0.5Ge0.5 alloy. Stability of the phase α against segregation into pure constituents is given by the formation enthalpy:where EX is the total energy per atom for X (= α, Si, Ge) at equilibrium. In the case of epitaxial growth, when the lattice constant of the epilayer in the plane of growth is equal to that of the substrate, the formation enthalpy takes the value (299)

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“…10 However, LeGoues, et al, with annealing experiments showed that annealing is not able to improve the ordering; in fact once the ordering is destroyed by high temperature processing further annealing is unable to restore it. 72 Reported growth temperatures to foster ordering are below 550 ˚C, generally in the proximity of 400 ˚C. [10][11][12]14,15,61,74 Kuan, et al, 13 Muller, et al, 11 and LeGoues, et al, 12,72 found that the ordering is not related to substrate strain and its existence is solely dependent upon the conditions of the dynamic growth surface.…”

Section: Ordering Mechanismmentioning

confidence: 99%

Synthesis and Characterization of Nano-to Meso Scale Ordered Structures in the Si1-xGex Alloy System

Amatya

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This dissertation describes investigations of structural ordering in the Si-Ge material system from nano-to-meso scale in order to modify electronic and thermal transport properties for potential improvement in thermoelectric or nanoelectronics applications.We first present the synthesis and characterization of mono-layer scale chemically ordered Si1-xGex alloys. Here, metastable ordering to an L11-like structure, occurring during

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Surface-stress-induced order in SiGe alloy films

Cited by 158 publications

References 14 publications

Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Thermodynamic Stability of Two Rhombohedral Phases of Si_0.5Ge_0.5Alloy

Synthesis and Characterization of Nano-to Meso Scale Ordered Structures in the Si1-xGex Alloy System

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Surface-stress-induced order in SiGe alloy films

Cited by 158 publications

References 14 publications

Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Initial stages of SiGe epitaxy on Si(001) studied by scanning tunneling microscopy

Thermodynamic Stability of Two Rhombohedral Phases of Si0.5Ge0.5Alloy

Synthesis and Characterization of Nano-to Meso Scale Ordered Structures in the Si1-xGex Alloy System

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Thermodynamic Stability of Two Rhombohedral Phases of Si_0.5Ge_0.5Alloy