Fabrication of compositional graded Si1−xGex layers by using thermal oxidation

Jang, Jae Hyuk; Son, S. Y.; Lim, Wantae; Phen, M.S.; Siebein, Kerry; Pearton, S. J.; Crăciun, V.

doi:10.1063/1.3139070

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…It is possible that oxidation of thicker intrinsic SiGe layers would demonstrate this more clearly by ensuring a longer plateau and distance between the pile-up region and the substrate. Another approach is presented by Jang et al, 14 who look at pile-up effects at multiple temperatures for a single oxidation time. Although most authors conclude that temperature does influence the Ge profile, they do not effectively compare one temperature to another, because the use of one oxidation time for multiple temperatures results in different amounts of Si having been removed from the SiGe layer by oxidation.…”

Section: B Ge Redistribution and The Pile-up Layermentioning

confidence: 99%

“…Such concentration gradients are typically characterized by a Ge-rich region adjacent to the SiO 2 growth front and are variously referred to as a pile-up region, snow plow effect, or germanium-rich layer (GRL). The pile-up effect, resulting from dry oxidation of SiGe, has been reported to occur in numerous publications, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] but these observations are frequently limited to the acknowledgment of the existence of a pile-up layer. Furthermore, the reports do not provide sufficient information to understand how modification of the oxidation conditions may lead to variations in the profile of Ge concentration in the SiGe.…”

Section: Introductionmentioning

confidence: 99%

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Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Long

Azarov

Kløw

et al. 2012

Journal of Applied Physics

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Several fundamental aspects of the oxidation-induced redistribution of Ge in thin films of SiGe are studied. This includes the incorporation of Ge into the oxide and the formation of what is alternatively referred to as pileup , snow-plow, or a germanium-rich layer. Experimental data from the present work shows longer oxidation times leading to an increase of Ge content in the pileup region and eventually creating a single high Ge content pileup layer by entirely consuming the initial SiGe layer. The pileup effect was shown to occur at the oxidation interface, with the highest Ge content occurring at the same interface. For a given oxide thickness, the redistribution of Ge and the formation of a pileup region was shown experimentally to be independent of temperature in the range between 800 C and 1000 C. Simulations using common models for the oxidation of Si and diffusion of Si in SiGe indicate that temperature does have an influence on the composition of the pileup layer, though the range of achievable compositions is limited. The flux of Si due to diffusion of Si in SiGe relative to the oxidation-induced flux of Si out of the SiGe is integral to the formation and dimensions of a pileup region. Two predictive relations were derived for describing the dynamics of oxidation of SiGe. The first relation is given for determining the pileup layer thickness as a function of oxide thickness and the composition of the pileup layer. The second relation assumes a limited supply of Si and is for determination of the minimum initial thickness of a SiGe layer to avoid oxidation of Ge. The validity of these equations was confirmed experimentally by RBS and XPS data from the present work. The proposed models may be used in nanostructuring of thin films of SiGe by oxidation and in the design of core-shell structures and transistors. This is all done with a focus on oxidation of epitaxial thin films (< 100 nm) of Si 1-X Ge X in dry O 2 at 1 atm between 800 C and 1000 C. V

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Section: B Ge Redistribution and The Pile-up Layermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Long

Azarov

Kløw

et al. 2012

Journal of Applied Physics

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“…The two phenomena commonly discussed in the literature about oxidation of SiGe are the potential for Ge to act as a catalyst or inhibitor for oxidation, and the formation of a Ge-rich layer between the oxide and the underlying SiGe, referred to as Ge condensation, pile-up, or snow plowing. [22][23][24][25][26][27][28][29][30] A common explanation for the presumed catalytic effect of Ge relies on the dissociation energy for a Si-Ge bond being lower than that of a Si-Si bond, [31][32][33][34][35] while others explain Ge's role as a catalyst in terms of the generation of vacancies and interstitials in the SiGe layers. [22][23][24][25][36][37][38] However, conclusions about the role of Ge in determining the oxidation rate vary widely, and the Ge content at the oxidation interface is rarely characterized in a systematic way.…”

Section: Introductionmentioning

confidence: 99%

Nano-structuring in SiGe by oxidation induced anisotropic Ge self-organization

Long

Galeckas

Kuznetsov

et al. 2013

Journal of Applied Physics

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The present study examines the kinetics of dry thermal oxidation of (111), (110), and (100) silicon-germanium (SiGe) thin epitaxial films and the redistribution of Ge near the oxidation interface with the aim of facilitating construction of single and multi-layered nano-structures. By employing a series of multiple and single step oxidations, it is shown that the paramount parameter controlling the Ge content at the oxidation interface is the oxidation temperature. The oxidation temperature may be set such that the Ge content at the oxidation interface is increased, kept static, or decreased. The Ge content at the oxidation interface is modeled by considering the balance between Si diffusion in SiGe and the flux of Si into the oxide by formation of SiO 2. The diffusivity of Si in SiGe under oxidation is determined for the three principal crystal orientations by combining the proposed empirical model with data from X-ray diffraction and variable angle spectroscopic ellipsometry. The orientation dependence of the oxidation rate of SiGe was found to follow the order: ð111Þ > ð110Þ > ð100Þ. The role of crystal orientation, Ge content, and other factors in the oxidation kinetics of SiGe versus Si are analyzed and discussed in terms of relative oxidation rates. V

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“…4 Oxidation of an epitaxial Si 1−x Ge x layer has been used to increase the Ge concentration of Si 1-x Ge x in other studies. [5][6][7] Selective oxidation of Si results in the accumulation of the Ge atoms between SiO 2 and the remaining Si 1x Ge x layer, as result of the snowplowing effect.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of a Channel Strain via Dry Oxidation of Recessed Source/Drain Si_1−xGe_x Structures

Kim

Yoo²,

Koo³

et al. 2011

ECS Trans.

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We investigated the effects of oxidation on recessed source/drain Si1-xGex structures. Epitaxial Si1-xGex films were deposited on recessed source/drain structures using a selective epitaxial growth process combined with ultrahigh-vacuum chemical vapor deposition and oxidized in dry oxygen ambient. Based on nano beam diffraction analyses, the channel strain was effectively enhanced at specific oxidation conditions. The increase in channel strain results from the formation of Ge-rich layers on the top surface of the Si1-xGex regions upon oxidation.

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Fabrication of compositional graded Si1−xGex layers by using thermal oxidation

Abstract: Articles you may be interested inEffects of stress on the dielectric function of strained pseudomorphic Si1−xGex alloys from 0 to 75% Ge grown on Si (001)

Cited by 7 publications

References 17 publications

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Nano-structuring in SiGe by oxidation induced anisotropic Ge self-organization

Enhancement of a Channel Strain via Dry Oxidation of Recessed Source/Drain Si_1−xGe_x Structures

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Fabrication of compositional graded Si1−xGex layers by using thermal oxidation

Abstract: Articles you may be interested inEffects of stress on the dielectric function of strained pseudomorphic Si1−xGex alloys from 0 to 75% Ge grown on Si (001)

Cited by 7 publications

References 17 publications

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Ge redistribution in SiO2/SiGe structures under thermal oxidation: Dynamics and predictions

Nano-structuring in SiGe by oxidation induced anisotropic Ge self-organization

Enhancement of a Channel Strain via Dry Oxidation of Recessed Source/Drain Si1−xGex Structures

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Enhancement of a Channel Strain via Dry Oxidation of Recessed Source/Drain Si_1−xGe_x Structures