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Penn, C.; Schäffler, F.; Bauer, G.; Glutsch, S.

doi:10.1103/physrevb.59.13314

Cited by 44 publications

(28 citation statements)

References 12 publications

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“…For the case of unstrained Si/Ge, Δ , between Si and Ge was calculated to be between 500 and 700 meV. 5,6 Using the deformation potentials in Table II, which are justified in the Appendix, we adjusted the value of Δ , to reproduce the 40 meV type II band offset at the Si 0.70 Ge 0.30 /Si, as observed by Thewalt et al 11,12 We obtain an exact fit using Δ , = 800 meV.…”

Section: Unified Theoretical Description Of the Si-ge Systemmentioning

confidence: 99%

“…6,10), whereas experimental results for s-Si 0.70 Ge 0.30 /unstrained-Si clearly show that the alignment is type II (lower conduction band-edge in Si). 11,12 Rieger and Vogl 9 do predict a type II alignment for s-Si 0.70 Ge 0.30 /unstrained-Si, but they use theoretical hydrostatic deformation potentials for the Δ-minimum indirect band gap that differ from experimental values. Their theoretical deformation potential for Si is much larger and for Ge is of opposite sign compared to experimental values.…”

Section: Introductionmentioning

confidence: 99%

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Extraction of large valence-band energy offsets and comparison to theoretical values for strained-Si/strained-Ge type-II heterostructures on relaxed SiGe substrates

et al. 2012

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MOS-capacitors were fabricated on type II staggered gap strained-Si/strained-Ge heterostructures epitaxially grown on relaxed SiGe substrates of various Ge fractions. Quasistatic quantum mechanical capacitance-voltage (CV) simulations were fit to experimental CV measurements to extract the band alignment of the strained layers. The valence band offset of the strained-Si/strained-Ge heterostructure was found to be 770, 760, and 670 meV for 35, 42, and 52% Ge in the relaxed SiGe substrate, respectively. These values are approximately 100 meV larger than expected on the basis of the usually recommended band offsets for modeling Si/Ge structures. It is shown that the larger valence band offsets found here are consistent with an 800 meV average valence band offset between Si and Ge, which also explains the type II band alignment observed in strained-Si 1-x Ge x on unstrained-Si heterostructures.

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Section: Unified Theoretical Description Of the Si-ge Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extraction of large valence-band energy offsets and comparison to theoretical values for strained-Si/strained-Ge type-II heterostructures on relaxed SiGe substrates

et al. 2012

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“…1,[13][14][15][16] Furthermore, the energy band alignment at the interface between two differently composed Si 1−x Ge x layers is sensitive to the strain present in each layer. 1,[13][14][15] Van de Walle and Martin have performed band gap and band alignment calculations for Si/ Ge interfaces, 14 including calculations on Si 1−x Ge x alloys matched to either Si or Ge substrates. Their results can be used to estimate energy band discontinuities in the strained Si/ Ge material system.…”

Section: A Type-ii Band Alignment and Si/ Ge Intermixingmentioning

confidence: 99%

Growth-temperature-dependent band alignment inSi∕Gequantum dots from photoluminescence spectroscopy

Larsson

Elfving

et al. 2006

Phys. Rev. B

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The present work is a photoluminescence study of Si-embedded Stranski-Krastanov Ge quantum dots. The value of the conduction band offset is a result of the magnitude of the tensile strain in the Si surrounding the compressive strained Ge dot. Due to the increased Si/ Ge intermixing and reduced strain in the Si barrier, a reduction of the conduction band offset is observed at increased growth temperatures. The optical properties as derived from photoluminescence spectroscopy are correlated with structural properties obtained as a function of the growth temperature. High growth temperatures result in large Ge dots with low density due to the pronounced surface diffusion and Si/ Ge intermixing. As confirmed by photoluminescence, the band gap of the Ge dots increases with increased growth temperature due to the higher degree of Si/ Ge intermixing. The band alignment is of type II in these structures, but the occurrence of both spatially indirect and spatially direct transitions are confirmed in temperature-dependent photoluminescence measurements with varied excitation power conditions. An increasing temperature results in a gradual transition from the spatially indirect to the spatially direct recombination in the type-II band lineup, due to higher oscillator strength for the spatially direct transition combined with a higher population factor at higher temperatures.

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“…An interesting case to be studied is the system composed by a Si core wire, surrounded by a layer (internal shell) of Si 1-x Ge x and covered by a second layer (external shell) of Si. We consider that for a Ge concentration x = 0.30 this system exhibits a type-II potential for electrons in the conduction band, as in the case of core-shell wires we studied and Si/Si 1-x Ge x quantum wells in literature (Penn et al, 1999). The type-II Si/Si 1-x Ge x /Si core-multi-shell quantum wires have an interesting feature: the Si 1-…”

Section: Type-i Simentioning

confidence: 99%

“…Then, in this work we study both types of confinement, for the appropriate Ge concentrations in each case. The material parameters for Si and Ge can be easily found in litterature (Penn et al, 1999) and the parameters of the alloy were obtained by interpolation of those of the pure materials. (10) is then performed numerically and, after the minimization, we eventually obtain the total exciton energy as exc gap ehb EEE E E =+ + − , where gap E is the gap of the core material.…”

Section: Core-shell Quantum Wiresmentioning

confidence: 99%

Quantum Confinement in Heterostructured Semiconductor Nanowires with Graded Interface

Farias¹,

Sousa²,

Chaves³

2010

Nanowires

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Where m and m ⊥ are the in-plane and longitudinal effective masses, respectively, andis the cyclotron frequency. In core-shell wires, we consider a potential V which includes not only the heterostructure, but also the electron-hole Coulomb potential. For the zinc-blend materials we studied, the valence band presents heavy and light hole states and, since in block-by-block wires the charge carriers are confined in three dimensions, the valence band states cannot be discussed in terms of a single hole state and a multi-band k.p study is necessary in this case. Hence, in this work we study excitonic effects only for core-

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Application of numerical exciton-wave-function calculations to the question of band alignment inSi/Si1−x

Cited by 44 publications

References 12 publications

Extraction of large valence-band energy offsets and comparison to theoretical values for strained-Si/strained-Ge type-II heterostructures on relaxed SiGe substrates

Extraction of large valence-band energy offsets and comparison to theoretical values for strained-Si/strained-Ge type-II heterostructures on relaxed SiGe substrates

Growth-temperature-dependent band alignment inSi∕Gequantum dots from photoluminescence spectroscopy

Quantum Confinement in Heterostructured Semiconductor Nanowires with Graded Interface

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