Growth and characterization of compositionally graded, relaxed Si1-xGex

Larsen, A. Nylandsted; Hansen, J. Lundsgaard; Jensen, Ralf Schou; Shiryaev, S. Yu.; Østergaard, Peter Riis; Hartung, J.; Davies, Gordon; Jensen, Flemming; Petersen, J. W.

doi:10.1088/0031-8949/1994/t54/052

Cited by 34 publications

(12 citation statements)

References 18 publications

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“…Samples with xϾ0.50 were not studied due to the unsatisfactory crystalline quality obtained in this composition range. The growth technique and the characterization of the Si 1Ϫx Ge x layers were described previously, 14,15 and only a brief account is given here. First, a 1-m Si layer was grown on a high-resistivity, float-zone, singlecrystalline, ͗100͘ Si wafer.…”

Section: Methodsmentioning

confidence: 99%

“…Transmission electron microscopy, photoluminescence, atomic force microscopy, and ion channeling measurements confirmed the high-crystalline quality of the Si 1Ϫx Ge x top layer. 14,15 Samples with typical dimensions of ϳ8ϫ8ϫ0.5 mm 3 were cut from the wafers, and the 8ϫ8 mm 2 backside surface of the Si substrate was mechanically polished to ensure large transmission of infrared light.…”

Section: Methodsmentioning

confidence: 99%

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Substitutional carbon inSi1−xGex

et al. 1999

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Local vibrational modes of carbon impurities in relaxed Si 1Ϫx Ge x have been studied with infrared absorption spectroscopy in the composition range 0.05рxр0.50. Carbon modes with frequencies in the range 512-600 cm Ϫ1 are observed in 13 C ϩ -implanted Si 1Ϫx Ge x after annealing at 550°C. Measurements on samples coimplanted with 12 C ϩ and 13 C ϩ show that these modes originate from defects containing a single carbon atom and from the variation of the mode frequencies with composition x, the modes are assigned to substitutional carbon in Si 1Ϫx Ge x . Based on the frequencies obtained from a simple vibrational model, the observed modes are assigned to specific combinations of the four Si and Ge neighbors to the carbon. The intensities of the modes indicate that the combination of the four neighbors deviates from a random distribution. Ab initio local-densityfunctional cluster theory has been applied to calculate the structure and the local mode frequencies of substitutional carbon with n Ge and 4Ϫn Si neighbors in a Si and a Ge cluster. The calculated frequencies are ϳ9% higher than those observed, but the ordering and the splitting of the mode frequencies agree with our assignments.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Substitutional carbon inSi1−xGex

et al. 1999

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“…[3][4][5][6][7]. It is sufficient to mention here that (i) all the structures are grown in the molecular-beam epitaxy (MBE) facility at the University of Aarhus; the variation of strain has been accomplished by growth on strain-relaxed SiGe layers of appropriate composition grown by either the compositional-grading technique [8] or the stepwise equilibrium technique [9], in both cases on (0 0 1)-oriented Si substrates, (ii) the high temperature diffusions are done in tube furnaces with either Ar or N 2 as protective gas (some of the samples have been capped by radio-frequency sputtered 100 nm SiO 2 and 100 nm Si 2 N 3 layers to shield the surface from reacting with the ambiance [6]), (iii) the dopant-depth profiles were measured with secondary-ion mass spectrometry (SIMS), and (iv) the layer thicknesses and compositions were checked with Rutherford-backscattering spectrometry (RBS), and it was ascertained with transmission-electron microscopy (TEM) that undesirable strain relaxation had not occurred. Fig.…”

Section: Methodsmentioning

confidence: 99%

The effect of biaxial strain on impurity diffusion in Si and SiGe

Larsen

Zangenberg

Fage-Pedersen

2005

Materials Science and Engineering: B

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Results from diffusion studies of different impurities in biaxially strained Si and Si 1 − x Ge x for low x-values will be presented. The structures are all molecular-beam epitaxy (MBE) grown on strain-relaxed Si 1 − x Ge x layers, and the impurity profiles are introduced during growth. We have in particular been concerned with the effect of biaxial strain (compressive and tensile) on the diffusion of pure vacancy-assisted diffusers (Sb and, partly, Ge) and pure interstitial-assisted diffusers (B and P). It is found that compressive biaxial strain retards the diffusion of the interstitial-assisted diffusers, whereas tensile biaxial strain enhances the diffusion of these impurities. The opposite is the case for the vacancy-assisted diffusers.

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“…To overcome this difficulty, a buffer layer of graded composition is first grown. Then, a thick Si 1−x Ge x alloy layer with a constant alloy composition is grown on top [5]. With this approach, the dislocations are confined to the buffer layer, enabling the densities to be limited to values as low as 10 4 cm −2 in the layer of interest.…”

Section: Introductionmentioning

confidence: 99%