Isotope effects in elemental semiconductors: a Raman study of silicon

Widulle, F.; Ruf, T.; Konuma, M.; Silier, I.; Cardona, M.; Kriegseis, W.; Ozhogin, V. I.

doi:10.1016/s0038-1098(01)00014-x

Cited by 84 publications

(56 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…17 Since the diffusivity of Si in SiO 2 is very low 18 and the implanted Si excess very high, the NCs are formed here by spinodal decomposition 12 and thus consist mainly of 28 Si, the isotope implanted. The Raman peak of 28 Si is shifted by about 1 cm −1 to higher frequencies 19 with respect to our natural Si reference. This effect compensates the downshift from the quantum confinement effect.…”

Section: Resonant Raman Scattering Of a Single Layer Of Si Nanocrystamentioning

confidence: 58%

Resonant Raman scattering of a single layer of Si nanocrystals on a silicon substrate

Wellner

Paillard

Coffin

et al. 2004

Journal of Applied Physics

View full text Add to dashboard Cite

We report Raman spectra of a single layer of silicon nanoparticles, spatially ordered in SiO2 at a tunneling distance from a silicon substrate. This is achieved by exploiting effects which enhance the nanocrystal signal, while suppressing the substrate one. The method is applied to investigate the structure of ion-implantation-produced Si nanoparticles annealed under different conditions. The results, which are in good agreement with transmission electron microscopy data, are used to explain photoluminescence measurements.

show abstract

Section: Resonant Raman Scattering Of a Single Layer Of Si Nanocrystamentioning

confidence: 58%

Resonant Raman scattering of a single layer of Si nanocrystals on a silicon substrate

Wellner

Paillard

Coffin

et al. 2004

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…(7) for n = 2, 3, 4 to the CPA values for the disorder-induced broadening of Si can be found in Ref. [ 12].…”

Section: Perturbation Theorymentioning

confidence: 99%

“…Raman studies that address the variation of the self-energy with the isotopic composition have been conducted for diamond [6][7][8][9][10][11] and Si. 12 The coherent potential approximation (CPA) has been employed for diamond [7][8][9] and Si 12 , while ab initio electronic structure based calculations have been performed for diamond and Ge. 13,14 All sets of data are analyzed with respect to the asymmetries of the self-energies and compared to the results we obtain by perturbation theory.…”

Section: Perturbation Theorymentioning

confidence: 99%

“…12 Within the harmonic approximation Γ dis = 0 for Si, Ge, and α-Sn, because the Raman frequency is at the maximum of the spectrum and thus corresponds to zero density of one-phonon states. The rather small, but non-negligible, observed value of Γ dis results from the DOS induced at the Γ-point by the anharmonic interactions responsible for the linewidth of the isotopically pure crystals.…”

Section: Perturbation Theorymentioning

confidence: 99%

See 1 more Smart Citation

Disorder-induced phonon self-energy of semiconductors with binary isotopic composition

2002

Self Cite

View full text Add to dashboard Cite

Self-energy effects of Raman phonons in isotopically disordered semiconductors are deduced by perturbation theory and compared to experimental data.In contrast to the acoustic frequency region, higher-order terms contribute significantly to the self-energy at optical phonon frequencies. The asymmetric dependence of the self-energy of a binary isotope system m 1−x M x on the concentration of the heavier isotope mass x can be explained by taking into account second-and third-order perturbation terms. For elemental semiconductors, the maximum of the self-energy occurs at concentrations with 0.5 < x < 0.7, depending on the strength of the third-order term. Reasonable approximations are imposed that allow us to derive explicit expressions for the ratio of successive perturbation terms of the real and the imaginary part of the self-energy. This basic theoretical approach is compatible with Raman spectroscopic results on diamond and silicon, with calculations based on the coherent potential approximation, and with theoretical results obtained using ab initio electronic theory. The extension of the formalism to binary compounds, by taking into account the eigenvectors at the individual sublattices, is straightforward. In this manner, we interpret recent experimental results on the disorder-induced broadening of the TO (folded) modes of SiC with a 13 C-enriched carbon sublattice. 1,2

show abstract

“…The harmonic assumption for the initial state of the supercell is never perfect since even the zero-point motion is slightly anharmonic. 44 The assumption becomes increasingly worse as the temperature increases. However, it is only used for supercell preparation at t = 0.…”

Section: Supercell Preparation In Thermal Equilibriummentioning

confidence: 99%

Thermal conductivity of Si nanostructures containing defects: Methodology, isotope effects, and phonon trapping

et al. 2011

View full text Add to dashboard Cite

A first-principles method to calculate the thermal conductivity in nanostructures that may contain defects or impurities is described in detail. The method mimics the so-called "laser-flash" technique to measure thermal conductivities. It starts with first-principles density-functional theory and involves the preparation of various regions of a supercell at slightly different temperatures. The temperature fluctuations are minimized without using a thermostat and, after averaging over random initial conditions, temperature changes as small as 5 K can be monitored (from 120 to 125 K). The changes to the phonon density of states and the specific heat induced by several atomic percent of impurities are discussed. The thermal conductivity of Si supercells is calculated as a function of the temperature and of the impurity content. For most impurities, the drop in thermal conductivity is unremarkable. However, there exist narrow ranges of impurity parameters (mass, bond strength, etc.) for which substantial drops in the thermal conductivity are predicted. These drops are isotope dependent and appear to be related to the vibrational lifetime of specific impurity-related modes.

show abstract

Isotope effects in elemental semiconductors: a Raman study of silicon

Cited by 84 publications

References 65 publications

Resonant Raman scattering of a single layer of Si nanocrystals on a silicon substrate

Resonant Raman scattering of a single layer of Si nanocrystals on a silicon substrate

Disorder-induced phonon self-energy of semiconductors with binary isotopic composition

Thermal conductivity of Si nanostructures containing defects: Methodology, isotope effects, and phonon trapping

Contact Info

Product

Resources

About