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2 Jun 2008

Volume 92, Issue 22, Articles (22xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 222502 (2008); http://dx.doi.org/10.1063/1.2937305 (3 pages)

Joseph Pingenot, Craig E. Pryor, and Michael E. Flatté
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Modulated terahertz responses of split ring resonators by nanometer thick liquid layers

Yimin Sun, Xiaoxiang Xia, Hui Feng, Haifang Yang, Changzhi Gu, and Li Wang

Appl. Phys. Lett. 92, 221101 (2008); http://dx.doi.org/10.1063/1.2939215 (3 pages) | Cited 13 times

Online Publication Date: 2 June 2008

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The terahertz responses of planar arrays of split ring resonators with 50 nm thin liquid layers introduced in the interspaces between the metal structures have been studied using the terahertz-time domain spectroscopy technique. In our experimental configuration, both the circular current driven and linear polarization induced resonances show redshifted and enhanced transmission. The dielectric functions extracted from an effective medium model indicate that the behavior of the surface and interface charge oscillations is highly sensitive to the interface environment changes. The results suggest that this kind of device may be used for sensing applications.
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42.25.Bs Wave propagation, transmission and absorption
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Generation of a squeezing vacuum at a telecommunication wavelength with periodically poled LiNbO3

Jinxia Feng, Xiutao Tian, Yongmin Li, and Kuanshou Zhang

Appl. Phys. Lett. 92, 221102 (2008); http://dx.doi.org/10.1063/1.2938053 (3 pages) | Cited 10 times

Online Publication Date: 2 June 2008

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A continuous-wave squeezed vacuum at a telecommunication wavelength was reported. Using an Er-doped fiber amplifier seeded by a single-frequency laser diode as the pump laser source, via a frequency doubler and an optical parametric oscillator based on periodically poled LiNbO3, the squeezed vacuum of 2.4±0.1 dB below the shot noise limit at 1560 nm was observed (the inferred initial squeezing is about 6.4±0.5 dB). This system is compatible with standard telecommunication optical fiber, and will be useful for long-distance quantum communication and distributed quantum computing.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.55.Wd Fiber lasers
42.70.Mp Nonlinear optical crystals
42.65.Lm Parametric down conversion and production of entangled photons

Highly efficient broadband second harmonic generation using polydomain epitaxial barium titanate thin film waveguides

Pao Tai Lin, B. W. Wessels, Joon I. Jang, and J. B. Ketterson

Appl. Phys. Lett. 92, 221103 (2008); http://dx.doi.org/10.1063/1.2936934 (3 pages) | Cited 3 times

Online Publication Date: 2 June 2008

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Broad band second harmonic generation (SHG) over the spectral range of 530–700 nm is reported using an epitaxial barium titanate (BaTiO3) thin film waveguide. The epitaxial layers are multidomain consisting of both a and c domain variants. The SHG conversion efficiency is nearly independent of wavelength over the visible spectra range. An enhanced broadband conversion efficiency was observed that is attributed to random quasi-phase matching in the polydomain epitaxial layers. In contrast to theory of SHG for disordered nonlinear media, the observed SHG shows a quadratic dependence on pump power.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Gn Optical waveguides and couplers

Monolithic rare-earth doped sol-gel tapered rib waveguide laser

A. Peled, A. Chiasera, M. Nathan, M. Ferrari, and S. Ruschin

Appl. Phys. Lett. 92, 221104 (2008); http://dx.doi.org/10.1063/1.2936961 (3 pages) | Cited 9 times

Online Publication Date: 2 June 2008

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We report the design, fabrication, and characterization of a monolithic tapered rib waveguide laser made of Nd doped silica hafnia sol-gel. The laser has a 604 nm thick guiding layer. CW pumping was coupled in via a grating which also coupled out the lasing signal output, while reflection gratings supported the feedback. A lasing threshold of 20 mW and an output power of 2.45 mW were measured in a 3 cm long device.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
42.86.+b Optical workshop techniques
42.79.Gn Optical waveguides and couplers
42.79.Dj Gratings

Monte Carlo simulation of extraction barrier width effects on terahertz quantum cascade lasers

H. Li, J. C. Cao, J. T. Lü, and Y. J. Han

Appl. Phys. Lett. 92, 221105 (2008); http://dx.doi.org/10.1063/1.2939435 (3 pages) | Cited 18 times

Online Publication Date: 3 June 2008

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The effect of extraction barrier width on the performance of a resonant-phonon terahertz quantum cascade laser is studied using the ensemble Monte Carlo method. The width of extraction barrier is varied from 48 to 33 Å with a stepsize of −3 Å. The calculated threshold current density increases monotonously from 436 to 1054 A/cm2 with decreasing extraction barrier width, while the peak gain shows nontrivial behavior. These findings agree well with an experimental study. The simulation results suggest an optimal extraction barrier width of 36 Å for peak gain and for the best temperature performance.
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42.60.By Design of specific laser systems

A phase feature extraction technique for terahertz reflection spectroscopy

Hua Zhong, Cunlin Zhang, Liangliang Zhang, Yuejin Zhao, and Xi-Cheng Zhang

Appl. Phys. Lett. 92, 221106 (2008); http://dx.doi.org/10.1063/1.2938055 (3 pages) | Cited 7 times

Online Publication Date: 3 June 2008

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We present a feature extraction technique for identification of explosive and biological materials using terahertz reflection time-domain spectroscopy (RTDS). The absorption signatures of the materials are extracted directly from the second-order derivative of the phase of the sample beam with respect to frequency. This technique provides a straightforward and fast solution to solve the phase-retrieval problem in RTDS and will benefit the future development of a standoff, large-size focal-plane terahertz sensing and imaging system.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
02.60.Lj Ordinary and partial differential equations; boundary value problems

Interference between two coherently driven monochromatic terahertz sources

S. Preu, S. Malzer, G. H. Döhler, Q. Z. Zhao, M. Hanson, J. D. Zimmerman, A. C. Gossard, and L. J. Wang

Appl. Phys. Lett. 92, 221107 (2008); http://dx.doi.org/10.1063/1.2938874 (3 pages) | Cited 3 times

Online Publication Date: 3 June 2008

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We report the interference between two phase-locked, continuous-wave, and coherent terahertz (Thz) photomixers. Both spatial and temporal coherence are observed with a narrow linewidth of less than 10 MHz. Phase locking is achieved by using one pair of lasers for both sources. The concept of optical narrow linewidth (fiber) distribution of the mixing signal opens various applications. We outline the necessary steps to extend this scheme for very long base line interferometric THz detection in the tens of kilometer range and for the improvement of spatial resolution for active stand-off THz imaging.
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42.25.Hz Interference
42.25.Kb Coherence
42.60.Fc Modulation, tuning, and mode locking

Quantum dot-embedded microspheres for remote refractive index sensing

Shuo Pang, Richard E. Beckham, and Kenith E. Meissner

Appl. Phys. Lett. 92, 221108 (2008); http://dx.doi.org/10.1063/1.2937209 (3 pages) | Cited 17 times

Online Publication Date: 3 June 2008

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We present a refractometric sensor based on quantum dot-embedded polystyrene microspheres. Optical resonances within a microsphere, known as whispering-gallery modes (WGMs), produce narrow spectral peaks. For sensing applications, spectral shifts of these peaks are sensitive to changes in the local refractive index. In this work, two-photon excited luminescence from the quantum dots couples into several WGMs within the microresonator. By optimizing the detection area, the spectral visibility of the WGMs is improved. The spectral shifts are measured as the surrounding index of the refraction changes. The experimental sensitivity is about five times greater than that predicted by the Mie theory.
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87.85.fk Biosensors
87.80.Ek Mechanical and micromechanical techniques
87.63.L- Visual imaging
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
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High-brightness relaxed-bend state in a pi cell stabilized by synchronized polymerization

Bo-Ru Yang, Steve J. Elston, Peter Raynes, and Han-Ping D. Shieh

Appl. Phys. Lett. 92, 221109 (2008); http://dx.doi.org/10.1063/1.2939559 (3 pages) | Cited 3 times

Online Publication Date: 5 June 2008

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The authors report a synchronized polymer-stabilization technique which can be used to stabilize the nonpermanent states in liquid crystal devices. In this paper, a relaxed-bend state in a pi cell which has a lifetime of only 80 ms is observed and then stabilized by this proposed technique. After stabilizing, the pi cell is immune to undesirable recovery into the splay or twist states, and its optical contrast is much higher than that of the conventional polymer-stabilized pi cell.
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42.79.Kr Display devices, liquid-crystal devices

Optical properties of yellow light-emitting diodes grown on semipolar (11math2) bulk GaN substrates

Hitoshi Sato, Roy B. Chung, Hirohiko Hirasawa, Natalie Fellows, Hisashi Masui, Feng Wu, Makoto Saito, Kenji Fujito, James S. Speck, Steven P. DenBaars, and Shuji Nakamura

Appl. Phys. Lett. 92, 221110 (2008); http://dx.doi.org/10.1063/1.2938062 (3 pages) | Cited 52 times

Online Publication Date: 5 June 2008

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We demonstrate high power yellow InGaN single-quantum-well light-emitting diodes (LEDs) with a peak emission wavelength of 562.7 nm grown on low extended defect density semipolar (11math2) bulk GaN substrates by metal organic chemical vapor deposition. The output power and external quantum efficiency at drive currents of 20 and 200 mA under pulsed operation (10% duty cycle) were 5.9 mW, 13.4% and 29.2 mW, 6.4%, respectively. It was observed that the temperature dependence of the output power of InGaN LEDs was significantly smaller than that of AlInGaP LEDs.
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85.60.Jb Light-emitting devices
85.40.Sz Deposition technology

Intrinsic optical modulation mechanism in electro-optic crystals

A. Garzarella, R. J. Hinton, S. B. Qadri, and Dong Ho Wu

Appl. Phys. Lett. 92, 221111 (2008); http://dx.doi.org/10.1063/1.2940340 (3 pages) | Cited 2 times

Online Publication Date: 5 June 2008

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An intrinsic mechanism of optical intensity modulation occurring in electro-optic devices such as field sensors and modulators under applied fields is described. The optical modulation results from interactions between internally generated Fizeau interference patterns and electro-optic effects within the nonlinear crystal. Our results indicate that when phase matched with the conventional polarimetric signal, the intrinsic modulation mechanism can nearly double device sensitivity.
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42.70.-a Optical materials
42.79.Hp Optical processors, correlators, and modulators
78.20.Jq Electro-optical effects
42.65.-k Nonlinear optics
07.60.Ly Interferometers

Cross-sectional study of periodic surface structures on gallium phosphide induced by ultrashort laser pulse irradiation

E. M. Hsu, T. H. R. Crawford, C. Maunders, G. A. Botton, and H. K. Haugen

Appl. Phys. Lett. 92, 221112 (2008); http://dx.doi.org/10.1063/1.2936865 (3 pages) | Cited 15 times

Online Publication Date: 5 June 2008

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We present cross-sectional transmission electron microscopy studies of laser induced periodic surface structures (LIPSS) formed on gallium phosphide after irradiation with ultrashort laser pulses with a pulse duration of 150 fs and centered at a wavelength of 800 nm. LIPSS with spatial periods ( ∼ 165 nm) substantially smaller than the incident wavelength are found to have vertical profiles as high as ∼ 960 nm measured from the crest to the trough. The present observations provide important insights into the formation mechanisms of subwavelength LIPSS.
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68.35.bg Semiconductors
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors

Enhancement in microwave modulation efficiency of vertical cavity surface-emitting laser by optical feedback

Nemi Gavra, Valentina Ruseva, and Michael Rosenbluh

Appl. Phys. Lett. 92, 221113 (2008); http://dx.doi.org/10.1063/1.2940231 (3 pages) | Cited 4 times

Online Publication Date: 6 June 2008

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We investigate a versatile vertical cavity surface-emitting laser (VCSEL) with a slight optical feedback from a simple wedge positioned at a well determined distance from the VCSEL. We use such a laser in conjunction with a miniature Rb atomic cell to detect coherent population trapping (CPT) when the external cavity mode spacing frequency corresponds to half the hyperfine frequency of Rb. The feedback greatly enhances the rf modulation efficiency of the VCSEL and as a result we obtain high contrast CPT signals at an input of −16 dBm of rf modulation power compared to +1.25 dBm needed in the absence of the external cavity.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Focusing of hard x-rays to 16 nanometers with a multilayer Laue lens

Hyon Chol Kang, Hanfei Yan, Robert P. Winarski, Martin V. Holt, Jörg Maser, Chian Liu, Ray Conley, Stefan Vogt, Albert T. Macrander, and G. Brian Stephenson

Appl. Phys. Lett. 92, 221114 (2008); http://dx.doi.org/10.1063/1.2912503 (3 pages) | Cited 27 times

Online Publication Date: 6 June 2008

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We report improved results for hard x-ray focusing using a multilayer Laue lens (MLL). We have measured a line focus of 16 nm width with an efficiency of 31% at a wavelength λ = 0.064 nm (19.5 keV) using a partial MLL structure with an outermost zone width of 5 nm. The results are in good agreement with the theoretically predicted performance.
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07.85.-m X- and γ-ray instruments
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High rate reactive magnetron sputter deposition of titanium oxide

T. Kubart, D. Depla, D. M. Martin, T. Nyberg, and S. Berg

Appl. Phys. Lett. 92, 221501 (2008); http://dx.doi.org/10.1063/1.2938054 (3 pages) | Cited 12 times

Online Publication Date: 2 June 2008

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A systematic experimental study of reactive sputtering from substoichiometric targets of TiOx with x ranging from 0 to 1.75 is reported. Experimental results are compared with results from modeling. The developed model describes the observed behavior and explains the origins of the unexpectedly high deposition rate. The behavior is shown to originate from the presence of titanium suboxides at the target surface caused by preferential sputtering of the oxide. The model can be used for optimization of the target composition with respect to the deposition rate and film composition in a stable hysteresis-free reactive sputtering process.
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81.15.Cd Deposition by sputtering
68.55.at Other materials
68.55.Nq Composition and phase identification
61.66.Bi Elemental solids
61.66.Dk Alloys

A hard graphitelike hydrogenated amorphous carbon grown at high deposition rate (>15 nm/s)

S. V. Singh, M. Creatore, R. Groenen, K. Van Hege, and M. C. M. van de Sanden

Appl. Phys. Lett. 92, 221502 (2008); http://dx.doi.org/10.1063/1.2938056 (3 pages) | Cited 11 times

Online Publication Date: 2 June 2008

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Hard graphitelike hydrogenated amorphous carbon with distinct infrared absorption spectra in the C–Hx stretching region is reported. These spectra are characterized by two separated peaks corresponding predominantly to sp3 CH and sp2 CH stretching modes and reveal a distinct absence of endgroups (sp2 CH2 and sp3 CH3). The relatively dense films ( ∼ 2.1 g/cm3) have low hydrogen content ( ∼ 20%), high refractive index ( ∼ 2.4 at 3 μm), nanohardness exceeding 16 GPa, and a characteristic optical dispersion relation. These films are deposited at growth rates >15 nm/s, in the absence of high-energy ion bombardment, indicating the importance of the specific Ar–C2H2 chemistry of the remote plasma used.
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81.05.U- Carbon/carbon-based materials
68.55.-a Thin film structure and morphology
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.-w Optical properties of specific thin films

Gasless sputtering: Opportunities for ultraclean metallization, coatings in space, and propulsion

Joakim Andersson and André Anders

Appl. Phys. Lett. 92, 221503 (2008); http://dx.doi.org/10.1063/1.2938414 (3 pages) | Cited 27 times

Online Publication Date: 2 June 2008

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Pulsed magnetron sputtering was demonstrated in high vacuum: no sputter gas was used at any time. Sustained self-sputtering was initiated by multiply charged ions from a short vacuum arc. Copper ion currents to an ion collector in excess of 30 A were measured, implying a plasma density of about 6×1018 m−3. This technology may prove useful for metal coatings free of noble gas inclusions and suggests that magnetrons could operate in the vacuum of space. In addition to coating objects in space, the momentum of the sputtered atoms and ions may be utilized in space thrusters.
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81.15.Cd Deposition by sputtering
68.55.-a Thin film structure and morphology
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

Guo Li, He-Ping Li, Li-Yan Wang, Sen Wang, Hong-Xin Zhao, Wen-Ting Sun, Xin-Hui Xing, and Cheng-Yu Bao

Appl. Phys. Lett. 92, 221504 (2008); http://dx.doi.org/10.1063/1.2938692 (3 pages) | Cited 25 times

Online Publication Date: 3 June 2008

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Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.
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52.80.Hc Glow; corona
52.77.-j Plasma applications

Two dimensional expansion effects on angular distribution of 13.5 nm in-band extreme ultraviolet emission from laser-produced Sn plasma

K. L. Sequoia, Y. Tao, S. Yuspeh, R. Burdt, and M. S. Tillack

Appl. Phys. Lett. 92, 221505 (2008); http://dx.doi.org/10.1063/1.2938717 (3 pages) | Cited 8 times

Online Publication Date: 3 June 2008

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The angular distribution of extreme ultraviolet emission at 13.5 nm within 2% bandwidth was characterized for laser irradiated, planar, Sn targets at prototypic conditions for a lithography system. We have found that two dimensional plasma expansion plays a key role in the distribution of in-band 13.5 nm emission under these conditions. The angular distribution was found to have two peaks at 45° and 15°. This complex angular distribution arises from the shape of both the emitting plasma and the surrounding absorbing plasma. This research reveals that the detailed angular distribution can be important to the deduction of conversion efficiency.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Three-dimensional spatiotemporal behaviors of light emission from discharge plasma of alternating current plasma display panels

Tae-Seung Cho, Gu-Hyun Chung, and Jin-Woo Jung

Appl. Phys. Lett. 92, 221506 (2008); http://dx.doi.org/10.1063/1.2938074 (3 pages) | Cited 13 times

Online Publication Date: 5 June 2008

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Test panel for three-dimensional observation in ac plasma display panel (PDP) has been fabricated and the spatiotemporal behavior of infrared and visible emissions has been experimentally investigated in sustain discharges. Considering the infrared and visible emissions from the cathode, the cathode fall region in ac PDP could be within 70 μm in thicknesses. We measured the propagation speed of the sheath plasma to be 1.8 mm/μs. In addition, the experimental result showed that an increasing sustain frequency from 100 to 250 kHz improved the plasma efficiency.
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52.25.Tx Emission, absorption, and scattering of particles
52.75.-d Plasma devices
52.80.-s Electric discharges
52.40.Kh Plasma sheaths

Measurement of electron temperature and density in an argon microdischarge by laser Thomson scattering

Sergey G. Belostotskiy, Rahul Khandelwal, Qiang Wang, Vincent M. Donnelly, Demetre J. Economou, and Nader Sadeghi

Appl. Phys. Lett. 92, 221507 (2008); http://dx.doi.org/10.1063/1.2939437 (3 pages) | Cited 18 times

Online Publication Date: 6 June 2008

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Laser Thomson scattering in a novel, backscattered configuration was employed to measure the electron temperature (Te) and electron density (ne) in argon dc microdischarges, with an interelectrode gap of 600 μm. Measurements were performed at the center of the gap that corresponds to the positive column. For 50 mA microdischarge current and over the pressure range of 300–700 Torr, the plasma parameters were found to be Te = 0.9±0.3 eV and ne = (6±3)×1013 cm−3, in reasonable agreement with the predictions of a mathematical model.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.80.-s Electric discharges

Spatial evolution of an ion beam created by a geometrically expanding low-pressure argon plasma

C. S. Corr, R. W. Boswell, C. Charles, and J. Zanger

Appl. Phys. Lett. 92, 221508 (2008); http://dx.doi.org/10.1063/1.2938720 (3 pages) | Cited 8 times

Online Publication Date: 6 June 2008

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The spatial distribution of an ion beam—created at the interface of a small diameter plasma source and much larger diameter diffusion chamber—is studied in a low-pressure inductively coupled plasma using a retarding field energy analyzer. It is found that the ion beam density decays axially and radially in the diffusion chamber following the expansion of the plasma from the source region. The radial distribution of the ion beam indicates that the acceleration region has a convex shape and is located just outside the source exit, giving rise to a hemispherical plasma expansion into the diffusion chamber.
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52.50.Dg Plasma sources
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Effect of hydrogen incorporation temperature in in plane-engineered GaAsN/GaAsN:H heterostructures

R. Trotta, A. Polimeni, M. Capizzi, D. Giubertoni, M. Bersani, G. Bisognin, M. Berti, S. Rubini, F. Martelli, L. Mariucci, M. Francardi, and A. Gerardino

Appl. Phys. Lett. 92, 221901 (2008); http://dx.doi.org/10.1063/1.2939000 (3 pages) | Cited 8 times

Online Publication Date: 2 June 2008

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The influence of temperature on deuterium (or hydrogen) diffusion in GaAsN is investigated by secondary ion mass spectrometry and photoluminescence (PL). Deuterium incorporation at 200 °C leads to an extremely sharp D concentration profile, which decreases by a factor of 10 within 5 nm. This has great relevance to the attainment of an in-plane band gap engineering of dilute nitrides as demonstrated by PL in ensembles of artificial GaAsN wires.
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71.20.Nr Semiconductor compounds
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
66.30.J- Diffusion of impurities
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
61.72.sd Impurity concentration

Anomalous subharmonics excited by intensive ultrasonic pulses with a single frequency

Kai Zheng, Shu-yi Zhang, Zhao-jiang Chen, Li Fan, and Hui Zhang

Appl. Phys. Lett. 92, 221902 (2008); http://dx.doi.org/10.1063/1.2937405 (3 pages) | Cited 1 time

Online Publication Date: 2 June 2008

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Anomalous subharmonics named as quasisubharmonics (QSHs) in plates excited by intensive ultrasonic pulses are first observed, in which the QSH frequencies are incommensurable with the fundamental frequency. The experimental results show that the low (such as 1/3) order subharmonics appear in the transient process of the ultrasonic excitation, and then several QSHs successively appear as the ultrasonic power increases and approaches steady state, in which the first QSH appears near the system eigenfrequency. A phenomenological model is presented and the theoretical simulations indicate that the QSHs are produced by the intermittent contacts between the transducer horn and the plate.
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43.40.Qi Effect of sound on structures, fatigue; spatial statistics of structural vibration
43.40.At Experimental and theoretical studies of vibrating systems
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants

Anisotropy of crystal-melt interfacial free energy of silicon by simulation

Pankaj A. Apte and X. C. Zeng

Appl. Phys. Lett. 92, 221903 (2008); http://dx.doi.org/10.1063/1.2937444 (3 pages) | Cited 19 times

Online Publication Date: 2 June 2008

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We extend the cleaving wall method to a nonpairwise additive potential. Using this method, we compute the anisotropy of crystal-melt interfacial free energy γ for Stillinger–Weber potential of silicon [ F. H. Stillinger and T. A. Weber, Phys. Rev. B 31, 5262 (1985) ]. The calculated γ for (100), (111), and (110) orientations are 0.42±0.02, 0.34±0.02, and 0.35±0.03 J/m2, respectively. The anisotropy in γ we found is consistent with the experimental observation that Si(100)-melt interface develops (111) facets and also helps in explaining a higher undercooling observed for Si(111)-melt interface in Czochralski method.
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81.05.Cy Elemental semiconductors
81.10.Fq Growth from melts; zone melting and refining
68.35.Md Surface thermodynamics, surface energies
65.40.gp Surface energy
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