Bond-Length Distortions in Strained Semiconductor Alloys

Woicik, J. C.; Pellegrino, John; Steiner, Bruce; Miyano, K. E.; Bompadre, S. G.; Sorensen, L. B.; Lee, T.-L.; Khalid, Syed

doi:10.1103/physrevlett.79.5026

Cited by 73 publications

(30 citation statements)

References 14 publications

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“…(1), (2) and (3) An analytical model was developed in Ref. 37 for strained alloys. We compare our NEMO 3-D results for strained QW (blue line in figure 7(b)) with the analytical model [37] (red line in figure 7(b)).…”

Section: A Aspect Ratio Change Of the Quantum Dotmentioning

confidence: 99%

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Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Usman

Ryu

Woo

et al. 2009

IEEE Trans. Nanotechnology

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Abstract-Low-loss optical communication requires light sources at 1.5um wavelengths. Experiments showed without much theoretical guidance that InAs/GaAs quantum dots (QDs) may be tuned to such wavelengths by adjusting the In fraction in an In x Ga 1-x As strain-reducing capping layer (SRCL). In this work systematic multimillion atom electronic structure calculations qualitatively and quantitatively explain for the first time available experimental data. The NEMO 3-D simulations treat strain in a 15 million atom system and electronic structure in a subset of ~9 million atoms using the experimentally given nominal geometries and without any further parameter adjustments the simulations match the nonlinear behavior of experimental data very closely. With the match to experimental data and the availability of internal model quantities significant insight can be gained through mapping to reduced order models and their relative importance. We can also demonstrate that starting from simple models has in the past led to the wrong conclusions. The critical new insight presented here is that the QD changes its shape. The quantitative simulation agreement with experiment without any material or geometry parameter adjustment in a general atomistic tool leads us to believe that the era of nano Technology Computer Aided Design (nano-TCAD) is approaching. NEMO 3-D will be released on nanoHUB.org where the community Manuscript received July 13, 2008. This work was carried out in part at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Muhammad Usman is funded through Fulbright USAID (Grant ID # 15054783). nanoHUB.org computational resources operated by the Network for Computational Nanotechnology (NCN) funded by the National Science Foundation were used in this work.Copyright (c) 2008 IEEE. Personal use of this material is permitted. However, permission to use this material for any other purposes must be obtained from the IEEE by sending a request to pubs-permissions@ieee.org .Muhammad Usman is with the Network for Computational Nanotechnology, Electrical Engineering Department, Purdue University West Lafayette, Indiana 47907 USA can duplicate and expand on the results presented here through interactive simulations.

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Section: A Aspect Ratio Change Of the Quantum Dotmentioning

confidence: 99%

“…37 for strained alloys. We compare our NEMO 3-D results for strained QW (blue line in figure 7(b)) with the analytical model [37] (red line in figure 7(b)). A close qualitative match is found, to within 0.73%, validating the NEMO 3-D model.…”

Section: A Aspect Ratio Change Of the Quantum Dotmentioning

confidence: 99%

Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Usman

Ryu

Woo

et al. 2009

IEEE Trans. Nanotechnology

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“…14 The large size of the Bi atom exerts a strong local distortion of the bonds in its immediate vicinity, leading to a locally higher strain field. 14,22,28,29 This strain will therefore lift the degeneracy of the doublet and produce independent HH-like and LH-like transitions in the modulated reflectance spectra. To estimate the localized strain, we calculated the distorted Ga-As (r' GaAs ) and Ga-Bi (r' GaBi ) bond lengths in a pseudomorphically strained GaAs 1-x Bi x film according to the approach of Woicik, et al 29 using unstrained lattice constants of a GaAs = 5.653 Å and a GaBi =6.324 Å for…”

Section: E_(hh) and E_(lh) Levels We Find That The E_(hh) And E_(lh)mentioning

confidence: 99%

Direct observation of theE−resonant state inGaAs1−xBix
Alberi
¹
,
Beaton
²
,
Mascarenhas
³

2015
Phys. Rev. B
14
5
11
0
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“…For example, biaxial strain can introduce bondlength and bond-angle distortions in semiconductor alloys, [1,2,3,4]which greatly affect their performance in real applications. Room temperature ferroelectricity has been induced by lattice strain in SrTiO 3 thin films, a material that is not ferroelectric in the bulk [5,6].…”

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confidence: 99%

Strain-induced change in local structure and its effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

Xie

Budnick

Hines

et al. 2008

Applied Physics Letters

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We have used high-resolution Extended X-ray Absorption Fine-Structure and diffraction techniques to measure the local structure of strained La 0.5 Sr 0.5 CoO 3 films under compression and tension. The lattice mismatch strain in these compounds affects both the bond lengths and the bond angles, though the larger effect on the bandwidth is due to the bond length changes. The popular double exchange model for ferromagnetism in these compounds provides a correct qualitative description of the changes in Curie temperature T C , but quantitatively underestimates the changes. A microscopic model for ferromagnetism that provides a much stronger dependence on the structural distortions is needed.Epitaxial strain in thin films is often used to modify a material's physical properties and improve device performance. For example, biaxial strain can introduce bondlength and bond-angle distortions in semiconductor alloys, [1,2,3,4]which greatly affect their performance in real applications. Room temperature ferroelectricity has been induced by lattice strain in SrTiO 3 thin films, a material that is not ferroelectric in the bulk [5,6]. Enhanced magnetoresistance has been achieved in La 0.8 Ba 0.2 MnO 3 thin films at room temperature [7], which makes it a potential candidate for magnetic devices and sensors. The modification of physical properties using strain is also an important tool for understanding the physics of correlated electron materials. One longstanding question in the field is the origin of ferromagnetism in several poorly conducting transition-metal oxides. The most popular model has been Zener's double exchange mechanism (DE) [8]. In this paper we report results comparing the Curie Temperature with detailed structural measurements in strained films of La 0.5 Sr 0.5 CoO 3 (LSCO). While the predictions appear qualitatively correct, they do not quantitatively predict the correct dependence on lattice parameter and, therefore, bandwidth. Thus, either another mechanism or a modification to DE is needed.The perovskite, transition-metal oxide that has been most studied as a function of strain is the colossal magnetoresistive manganites [9]. The strain has been induced in several ways in manganites including films. The analysis of these experiments has examined how strain has mediated the ferromagnetic coupling via modification of the bandwidth W [8,10]. In the tight-binding model, the bandwidth W depends on the overlap integrals between the Mn 3d and O 2p orbitals such that W ∝ d −3.5 cos ω [11,12], where d is Mn-O bond length, ω = (180 • − φ)/2 is the tilt angle, and φ is Mn-O-Mn bond buckling. A decrease in the lanthanide ion radius by chemical substitution leads to a reduction of T C that has been attributed to an increase of the Mn-O-Mn bond angle with little change in the Mn-O bond length [13,14]. The opposite case is that compressive hydrostatic pressure increases T C due to a reduction in Mn-O bond length with little decrease in Mn-O-Mn bond angle [15]. However, for film studies no full consensus has been reached...

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Bond-Length Distortions in Strained Semiconductor Alloys

Cited by 73 publications

References 14 publications

Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Direct observation of theE−resonant state inGaAs1−xBix
Alberi
¹
,
Beaton
²
,
Mascarenhas
³

2015
Phys. Rev. B
14
5
11
0
View full text Add to dashboard Cite

Strain-induced change in local structure and its effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

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Bond-Length Distortions in Strained Semiconductor Alloys

Cited by 73 publications

References 14 publications

Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Moving Toward Nano-TCAD Through Multimillion-Atom Quantum-Dot Simulations Matching Experimental Data

Direct observation of theE−resonant state inGaAs1−xBixAlberi1, Beaton2, Mascarenhas3 2015Phys. Rev. B145110View full textAdd to dashboardCite

Strain-induced change in local structure and its effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

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Direct observation of theE−resonant state inGaAs1−xBix
Alberi
¹
,
Beaton
²
,
Mascarenhas
³

2015
Phys. Rev. B
14
5
11
0
View full text Add to dashboard Cite