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3 Dec 2007

Volume 91, Issue 23, Articles (23xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 91, 232101 (2007); http://dx.doi.org/10.1063/1.2818712 (3 pages)

T. Kita, D. Chiba, Y. Ohno, and H. Ohno
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Widely tunable single-mode quantum cascade laser source for mid-infrared spectroscopy

Benjamin G. Lee, Mikhail A. Belkin, Ross Audet, Jim MacArthur, Laurent Diehl, Christian Pflügl, Federico Capasso, Douglas C. Oakley, David Chapman, Antonio Napoleone, David Bour, Scott Corzine, Gloria Höfler, and Jérôme Faist

Appl. Phys. Lett. 91, 231101 (2007); http://dx.doi.org/10.1063/1.2816909 (3 pages) | Cited 37 times

Online Publication Date: 3 December 2007

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We demonstrate a compact, single-mode quantum cascade laser source continuously tunable between 8.7 and 9.4 μm. The source consists of an array of single-mode distributed feedback quantum cascade lasers with closely spaced emission wavelengths fabricated monolithically on a single chip and driven by a microelectronic controller. Our source is suitable for a variety of chemical sensing applications. Here, we use it to perform absorption spectroscopy of fluids.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking

Large spectral tuning of liquid microdroplets standing on a superhydrophobic surface using optical scattering force

A. Kiraz, S. Ç. Yavuz, Y. Karadağ, A. Kurt, A. Sennaroglu, and H. Çankaya

Appl. Phys. Lett. 91, 231102 (2007); http://dx.doi.org/10.1063/1.2821145 (3 pages) | Cited 7 times

Online Publication Date: 3 December 2007

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We demonstrate large spectral tuning of glycerol/water microdroplets standing on a superhydrophobic surface using the optical scattering force exerted by a 1064 nm Nd3+:YVO4 solid-state laser. Spectral tuning up to 30 nm is presented in the whispering gallery modes as a result of the deformation of the microdroplets toward a truncated prolate spheroid geometry. Observed large spectral tuning is also reported to be highly reversible. This demonstration can inspire novel, largely tunable optical switches or filters based on liquid microdroplets kept in a sealed chamber.
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78.35.+c Brillouin and Rayleigh scattering; other light scattering

Visible-wavelength laser action of ZnCdO/(Zn,Mg)O multiple quantum well structures

S. Sadofev, S. Kalusniak, J. Puls, P. Schäfer, S. Blumstengel, and F. Henneberger

Appl. Phys. Lett. 91, 231103 (2007); http://dx.doi.org/10.1063/1.2822889 (3 pages) | Cited 19 times

Online Publication Date: 4 December 2007

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We report on laser action of ZnCdO/ZnO quantum well structures up to room temperature under optical pumping. Prerequisite is a novel annealing step increasing the radiative efficiency of the low-temperature grown structures by more than one order of magnitude. The carrier states involved are localized making the lasing properties temperature robust. The longest wavelength reached so far is 490 nm.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
61.72.Cc Kinetics of defect formation and annealing

Spatially resolved pump-probe second harmonic generation study of multilayer semiconductor heterostructures

Y. D. Glinka, N. H. Tolk, X. Liu, Y. Sasaki, and J. K. Furdyna

Appl. Phys. Lett. 91, 231104 (2007); http://dx.doi.org/10.1063/1.2821120 (3 pages) | Cited 2 times

Online Publication Date: 4 December 2007

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The transient electric-field-induced second harmonic generation change (TEFISHGC) signals from GaAs/GaSb/InAs heterostructures measured in pump-probe configuration have been applied to monitor the interfacial electric fields arising from the charge separation of pump-induced carriers at the interfaces. The total intensity of the TEFISHGC signal is determined by the interference of contributions from both of the heterointerfaces. By changing the photon energy of the laser light over the GaAs absorption edge, the depth spatial resolution can be achieved allowing the ultrafast dynamics of interfacial electric field at each of the interfaces to be monitored separately.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
68.65.Ac Multilayers
78.66.Fd III-V semiconductors

Templated fabrication of large area subwavelength antireflection gratings on silicon

Chih-Hung Sun, Wei-Lun Min, Nicholas C. Linn, Peng Jiang, and Bin Jiang

Appl. Phys. Lett. 91, 231105 (2007); http://dx.doi.org/10.1063/1.2821833 (3 pages) | Cited 42 times

Online Publication Date: 5 December 2007

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We report a cheap and scalable bottom-up technique for fabricating wafer-scale, subwavelength-structured antireflection coatings on single-crystalline silicon substrates. Spin-coated monolayer colloidal crystals are utilized as shadow masks to generate metallic nanohole arrays. Inverted pyramid arrays in silicon can then be templated against nanoholes by anisotropic wet etching. The resulting subwavelength gratings greatly suppress specular reflection at normal incidence. The reflection spectra for flat silicon and the templated gratings at long wavelengths agree well with the simulated results using a rigorous coupled wave analysis model. These subwavelength gratings are of great technological importance in crystalline silicon solar cells.
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42.79.Dj Gratings
42.86.+b Optical workshop techniques
42.79.Wc Optical coatings
84.60.Jt Photoelectric conversion

Substrate removal for high quantum efficiency back side illuminated type-II InAs/GaSb photodetectors

Pierre-Yves Delaunay, Binh Minh Nguyen, Darin Hofman, and Manijeh Razeghi

Appl. Phys. Lett. 91, 231106 (2007); http://dx.doi.org/10.1063/1.2821834 (3 pages) | Cited 8 times

Online Publication Date: 5 December 2007

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A substrate removal technique using an InAsSb etch stop layer improves by a factor of 2 the quantum efficiency of back side illuminated type-II InAs/GaSb superlattice photodetectors. After etching of the GaSb substrate with a CrO3 based solution, the quantum efficiency of the diodes presents Fabry-Pérot oscillations averaging at 56%. Due to the confinement of the infrared light inside the devices, the quantum efficiency for certain devices reaches 75% at 8.5 μm. The implementation of this new technique to a focal plane array resulted in a decrease of the integration time from 0.23 to 0.08 ms.
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81.65.Cf Surface cleaning, etching, patterning
68.47.Fg Semiconductor surfaces
81.05.Ea III-V semiconductors
85.60.Gz Photodetectors (including infrared and CCD detectors)
68.65.Cd Superlattices

Effect of threading defects on InGaN/GaN multiple quantum well light emitting diodes

M. S. Ferdous, X. Wang, M. N. Fairchild, and S. D. Hersee

Appl. Phys. Lett. 91, 231107 (2007); http://dx.doi.org/10.1063/1.2822395 (3 pages) | Cited 19 times

Online Publication Date: 5 December 2007

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Photoelectrochemical etching was used to measure the threading defect (TD) density in InGaN multiple quantum well light-emitting diodes (LEDs) fabricated from commercial quality epitaxial wafers. The TD density was measured in the LED active region and then correlated with the previously measured characteristics of these LEDs. It was found that the reverse leakage current increased exponentially with TD density. The temperature dependence of this dislocation-related leakage current was consistent with a hopping mechanism at low reverse-bias voltage and Poole-Frenkel emission at higher reverse-bias voltage. The peak intensity and spectral width of the LED electroluminescence were found to be only weakly dependent on TD density for the measured TD range of 1×107–2×108 cm−2.
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85.60.Jb Light-emitting devices
81.07.St Quantum wells
81.65.Cf Surface cleaning, etching, patterning

Wide-view transflective liquid crystal display for mobile applications

Hyang Yul Kim, Zhibing Ge, Shin-Tson Wu, and Seung Hee Lee

Appl. Phys. Lett. 91, 231108 (2007); http://dx.doi.org/10.1063/1.2822410 (3 pages) | Cited 24 times

Online Publication Date: 5 December 2007

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A high optical efficiency and wide-view transflective liquid crystal display based on fringe-field switching structure is proposed. The transmissive part has a homogenous liquid crystal (LC) alignment and is driven by a fringe electric field, which exhibits excellent electro-optic characteristics. The reflective part has a hybrid LC alignment with quarter-wave phase retardation and is also driven by a fringe electric field. Consequently, the transmissive and reflective parts have similar gamma curves.
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42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

InGaN/GaN light emitting diodes on nanoscale silicon on insulator

S. Tripathy, V. K. X. Lin, S. L. Teo, A. Dadgar, A. Diez, J. Bläsing, and A. Krost

Appl. Phys. Lett. 91, 231109 (2007); http://dx.doi.org/10.1063/1.2814062 (3 pages) | Cited 13 times

Online Publication Date: 5 December 2007

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The authors report on the fabrication of InGaN/GaN-based light emitting diodes (LEDs) on nanoscale silicon-on-insulator (SOI) substrates. The LED structures are grown on (111)-oriented 45 nm thick SOI overlayer by metal organic chemical vapor deposition. Square-shaped mesa patterns are created by standard LED processing steps including multiple-mask photolithography, inductive coupled plasma etching, and contact metallization. Due to the high reflective Si/SiO2 beneath AlN buffer and high refractive contrasts at the interfaces, the authors observed multiple interference peaks from LEDs on SOI and such effect resulted in an increased integrated electroluminescence intensity when compared to LED structures fabricated on bulk Si(111).
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85.60.Jb Light-emitting devices
85.60.Bt Optoelectronic device characterization, design, and modeling
78.60.Fi Electroluminescence

Wavelength tuning the photonic band gap in chiral nematic liquid crystals using electrically commanded surfaces

Su Seok Choi, Stephen M. Morris, Harry J. Coles, and Wilhelm T. S. Huck

Appl. Phys. Lett. 91, 231110 (2007); http://dx.doi.org/10.1063/1.2820681 (3 pages) | Cited 10 times

Online Publication Date: 5 December 2007

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In this letter, the authors demonstrate photonic band gap (PBG) tuning in chiral nematic liquid crystals using electrically commanded surfaces consisting of a ferroelectric liquid crystal. The electrically commanded surfaces generate a contraction of the pitch of the chiral nematic which is manifested as a blueshift of the PBG. Results are presented which demonstrate that tuning can be achieved by either varying the frequency or the amplitude of the electric field. The maximum shift observed for the long-wavelength band edge was 23 nm for an electric field strength of 20 V μm−1 and a frequency of 800 Hz to 1 kHz.
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42.70.Df Liquid crystals
42.70.Qs Photonic bandgap materials
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals

Low-loss quantum-dot-based saturable absorber for efficient femtosecond pulse generation

A. A. Lagatsky, F. M. Bain, C. T. A. Brown, W. Sibbett, D. A. Livshits, G. Erbert, and E. U. Rafailov

Appl. Phys. Lett. 91, 231111 (2007); http://dx.doi.org/10.1063/1.2817755 (3 pages) | Cited 12 times

Online Publication Date: 5 December 2007

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We report the efficient generation of femtosecond pulses from a diode-pumped solid-state laser that has been passively mode locked using a quantum-dot-based saturable absorber. Average output powers up to 1.15 W and transform-limited pulses as short as 114 fs were obtained around 1040 nm with a pulse repetition frequency of 107 MHz from a diode-pumped Yb3+:KY(WO4)2 laser. The InGaAs quantum-dot saturable absorber was characterized to have a saturation fluence of 25 μJ/cm2 and nonsaturable losses of less than 0.2% with an initial low-signal absorption of 2.5% at 1040 nm.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Deep periodic domain inversions in x-cut LiNbO3 and its use for second harmonic generation near 1.5 μm

Francis Généreux, Georges Baldenberger, Bruno Bourliaguet, and Réal Vallée

Appl. Phys. Lett. 91, 231112 (2007); http://dx.doi.org/10.1063/1.2820384 (3 pages) | Cited 4 times

Online Publication Date: 6 December 2007

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In this letter, we report the fabrication of deep x-cut periodically poled lithium niobate (PPLN) crystal. The technique relies on ridges performed by wet etching to improve poling field penetration into the substrate and, hence, to provide more depth to inverted domains. Based on this approach, domain inversions as deep as 6.5 μm were achieved. As an application, reverse proton exchanged waveguides were fabricated on top of the PPLN to demonstrate efficient second harmonic generation in the near infrared. A conversion efficiency as high as 46% W−1 cm−2 was measured near 1.5 μm.
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77.22.Ej Polarization and depolarization
81.65.Cf Surface cleaning, etching, patterning
77.80.Dj Domain structure; hysteresis
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

ZnO-on-GaN heterojunction light-emitting diode grown by vapor cooling condensation technique

Ricky W. Chuang, Rong-Xun Wu, Li-Wen Lai, and Ching-Ting Lee

Appl. Phys. Lett. 91, 231113 (2007); http://dx.doi.org/10.1063/1.2822817 (3 pages) | Cited 57 times

Online Publication Date: 6 December 2007

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The growth of ZnO-on-GaN heterostructures was implemented using the vapor cooling condensation system. The technique thus developed was employed to fabricate both the p-GaN/n-ZnO:In (p-n) and p-GaN/i-ZnO/n-ZnO:In (p-i-n) heterojunction light-emitting diodes (LEDs). A rectifying diodelike behavior was clearly observed from both the p-n and p-i-n heterojunction LEDs, with the forward turn-on voltage of 3 V and the reverse breakdown voltage of −15 V determined for the p-n heterojunction LEDs, compared to 7 and −23 V, respectively, for the p-i-n heterojunction LEDs. Based on the results of photoluminescence and electroluminescence studies conducted on these LED structures, the ZnO layer responsible for the peak emission wavelength of 385 nm were also verified experimentally.
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85.60.Jb Light-emitting devices
85.30.Kk Junction diodes

Effect of dislocation density on efficiency droop in GaInN/GaN light-emitting diodes

Martin F. Schubert, Sameer Chhajed, Jong Kyu Kim, E. Fred Schubert, Daniel D. Koleske, Mary H. Crawford, Stephen R. Lee, Arthur J. Fischer, Gerald Thaler, and Michael A. Banas

Appl. Phys. Lett. 91, 231114 (2007); http://dx.doi.org/10.1063/1.2822442 (3 pages) | Cited 90 times

Online Publication Date: 7 December 2007

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Measurements of light-output power versus current are performed for GaInN/GaN light-emitting diodes grown on GaN-on-sapphire templates with different threading dislocation densities. Low-defect-density devices exhibit a pronounced efficiency peak followed by droop as current increases, whereas high-defect-density devices show low peak efficiencies and little droop. The experimental data are analyzed with a rate equation model to explain this effect. Analysis reveals that dislocations do not strongly impact high-current performance; instead they contribute to increased nonradiative recombination at lower currents and a suppression of peak efficiency. The characteristics of the dominant recombination mechanism at high currents are consistent with processes involving carrier leakage.
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85.60.Jb Light-emitting devices

Geiger-mode avalanche photodiodes at 2 μm wavelength

E. K. Duerr, M. J. Manfra, M. A. Diagne, R. J. Bailey, J. P. Donnelly, M. K. Connors, and G. W. Turner

Appl. Phys. Lett. 91, 231115 (2007); http://dx.doi.org/10.1063/1.2822447 (2 pages) | Cited 3 times

Online Publication Date: 7 December 2007

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Geiger-mode avalanche photodiodes (APDs) with response at 2 μm have been developed in the antimonide material system. At 77 K, the APDs demonstrated a dark count rate of 210 kHz and an injection probability–avalanche probability product of 35% at 4.5 V of overbias.
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85.60.Dw Photodiodes; phototransistors; photoresistors
02.50.Cw Probability theory

Stability of the mode-locked regime in quantum dot lasers

E. A. Viktorov, Paul Mandel, M. Kuntz, G. Fiol, D. Bimberg, A. G. Vladimirov, and M. Wolfrum

Appl. Phys. Lett. 91, 231116 (2007); http://dx.doi.org/10.1063/1.2822808 (3 pages) | Cited 12 times

Online Publication Date: 7 December 2007

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We report on experimental and theoretical studies of the stability regime of passive mode-locked quantum dot lasers, which is decisively larger than in quantum well lasers. A small range of Q-switched instability is observed at low gain currents. Transition to Q switching is inhibited due to fast damping of the relaxation oscillations. A double pulse mode-locking regime appears for longer cavities, and exhibits bistability and coupling to the fundamental mode-locking operation.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
42.55.Ah General laser theory

Hydrothermal method grown large-sized zinc oxide single crystal as fast scintillator for future extreme ultraviolet lithography

Momoko Tanaka, Masaharu Nishikino, Hiroshi Yamatani, Keisuke Nagashima, Toyoaki Kimura, Yusuke Furukawa, Hidetoshi Murakami, Shigeki Saito, Nobuhiko Sarukura, Hiroaki Nishimura, Kunioki Mima, Yuji Kagamitani, Dirk Ehrentraut, and Tsuguo Fukuda

Appl. Phys. Lett. 91, 231117 (2007); http://dx.doi.org/10.1063/1.2815920 (3 pages) | Cited 14 times

Online Publication Date: 7 December 2007

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The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength. The exciton emission lifetime at around 380 nm is determined to be 1.1 ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3 in. is quite attractive for future lithography and imaging applications.
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81.10.Dn Growth from solutions
71.35.-y Excitons and related phenomena
78.55.Et II-VI semiconductors
78.40.Fy Semiconductors
78.20.-e Optical properties of bulk materials and thin films
85.40.Hp Lithography, masks and pattern transfer

Cavity polaritons from excited-subband transitions

Aji A. Anappara, Alessandro Tredicucci, Fabio Beltram, Giorgio Biasiol, Lucia Sorba, Simone De Liberato, and Cristiano Ciuti

Appl. Phys. Lett. 91, 231118 (2007); http://dx.doi.org/10.1063/1.2823584 (3 pages) | Cited 8 times

Online Publication Date: 7 December 2007

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We report on the coupling of optical transitions between excited conduction subbands in GaAs/AlGaAs heterostructures with the resonant photonic mode of a semiconductor microcavity. The coupling is found to increase with temperature, owing to the thermal excitation of carriers from the ground subband and, thanks to the large dipole-matrix element of the excited-state transition, a record splitting of 60 meV is shown in the room-temperature reflectance. The importance of translating the angle-dependent spectra into energy-wavevector dispersion when the coupling is so large is highlighted, and a theoretical fitting procedure is used to extract the value of the vacuum-field Rabi energy.
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71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.15.Qe Excited states: methodology
71.20.Nr Semiconductor compounds
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Enhancement of extreme ultraviolet emission from a CO2 laser-produced Sn plasma using a cavity target

Yoshifumi Ueno, Georg Soumagne, Akira Sumitani, Akira Endo, and Takeshi Higashiguchi

Appl. Phys. Lett. 91, 231501 (2007); http://dx.doi.org/10.1063/1.2820451 (3 pages) | Cited 24 times

Online Publication Date: 4 December 2007

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We demonstrated enhancement of in-band conversion efficiency (CE) at 13.5 nm of the extreme ultraviolet (EUV) emission from a tin (Sn) cavity target irradiated by a CO2 laser pulse. Whereas a planar Sn target produced an in-band CE of around 2%, the use of cavity targets significantly enhanced the EUV emission energy and the EUV CE. An EUV CE of 4% was observed for a Sn cavity target with a depth of 200 μm which is one of the highest values ever reported.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
42.72.Bj Visible and ultraviolet sources

Tunable low-energy Ar fast atom source with large diameter

Yasuhiro Hara, Seigo Takashima, Koji Yamakawa, Shoji Den, Hirotaka Toyoda, and Masaru Hori

Appl. Phys. Lett. 91, 231502 (2007); http://dx.doi.org/10.1063/1.2820444 (3 pages) | Cited 3 times

Online Publication Date: 6 December 2007

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We have developed a low-energy Ar fast atom source consisting of a surface wave plasma (SWP) source and two carbon electrodes with a diameter of 80 mm. Ions were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber and then neutralized by charge exchange reaction without energy loss. Characteristics of the Ar ions and Ar fast atoms were investigated using quadrupole mass spectroscopy with an energy analyzer. Energies of Ar fast atoms were successfully controlled from 20 to 80 eV by varying the acceleration voltage applied at the carbon electrode.
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29.25.-t Particle sources and targets
29.27.Ac Beam injection and extraction
29.27.Eg Beam handling; beam transport
52.75.-d Plasma devices

Broadband and time-resolved absorption spectroscopy with light emitting diodes: Application to etching plasma monitoring

G. Cunge, D. Vempaire, M. Touzeau, and N. Sadeghi

Appl. Phys. Lett. 91, 231503 (2007); http://dx.doi.org/10.1063/1.2822448 (3 pages) | Cited 14 times

Online Publication Date: 6 December 2007

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Broad band absorption spectroscopy is widely used to measure the concentration of radicals, which is important to understand the physical chemistry of many plasmas. It is possible to increase the sensitivity of this technique and to perform time-resolved measurement by using light emitting diodes (LEDs) as a light source. The method is applied to detect CF2 radicals and Cl2 molecules in high density plasmas. The detection limit over 10 ms integration time is as low as 3 mTorr of Cl2. We conclude that the absorption spectroscopy with LEDs opens possibilities for precise process control and fundamental analysis of reactive media.
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85.60.Jb Light-emitting devices
78.40.-q Absorption and reflection spectra: visible and ultraviolet
52.77.Bn Etching and cleaning

Radial evolution of dielectric barrier glowlike discharge in helium at atmospheric pressure

Haiyun Luo, Zhuo Liang, Bo Lv, Xinxin Wang, Zhicheng Guan, and Liming Wang

Appl. Phys. Lett. 91, 231504 (2007); http://dx.doi.org/10.1063/1.2823605 (3 pages) | Cited 10 times

Online Publication Date: 7 December 2007

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The radial evolution of dielectric barrier discharge in helium at atmospheric pressure was studied by taking end-view photographs of the discharge during one current pulse using a fast-gated intensified charge coupled device. The photographs were transformed into three-dimensional images that make the radial evolution of the discharge more visualized. It was found that the discharge begins with a weak Townsend discharge covering the entire electrode surface, develops much more rapidly in the central part where the electric field is higher, and spreads radially outward.
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52.80.Dy Low-field and Townsend discharges
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Multidimensional ZnO light-emitting diode structures grown by metal organic chemical vapor deposition on p-Si

Dong Chan Kim, Won Suk Han, Hyung Koun Cho, Bo Hyun Kong, and Hyoung Sub Kim

Appl. Phys. Lett. 91, 231901 (2007); http://dx.doi.org/10.1063/1.2820385 (3 pages) | Cited 20 times

Online Publication Date: 3 December 2007

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A multidimensional ZnO light-emitting diode (LED) structure comprising film/nanorods/substrate was fabricated on a p-type Si substrate using metal organic chemical vapor deposition at relatively low growth temperature. The filmlike top layer used for the metal contact was continuously formed on the ZnO nanorods by varying the growth conditions and the resulting structure allowed us to utilize the nanorods with intense emission as an active layer. We investigated the performance of the resulting multidimensional LED. An extremely high breakdown voltage and low reverse leakage current as well as typical rectification behavior were observed in the I-V characteristics.
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81.16.-c Methods of micro- and nanofabrication and processing
81.05.Dz II-VI semiconductors
73.63.Bd Nanocrystalline materials
77.22.Jp Dielectric breakdown and space-charge effects
85.60.Jb Light-emitting devices
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Measurement of incomplete strain relaxation in a silicon heteroepitaxial film by geometrical phase analysis in the transmission electron microscope

Jayhoon Chung and Lew Rabenberg

Appl. Phys. Lett. 91, 231902 (2007); http://dx.doi.org/10.1063/1.2821843 (3 pages) | Cited 4 times

Online Publication Date: 4 December 2007

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Relaxation of strain by a partial dislocation and stacking fault in a strained Si film was characterized using geometric phase analysis of high-resolution transmission electron microscope (HRTEM) images. Movement of a 60° glide dislocation from the free surface to the film-substrate interface created a complex state of strain in the film. HRTEM image analysis was used to produce a quantitative measure of the atomic displacement fields that could be used as input to finite-element simulations of stress distributions and resulting affects on band structures.
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68.60.Bs Mechanical and acoustical properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.72.Nn Stacking faults and other planar or extended defects
71.20.Mq Elemental semiconductors

High-geometrical-resolution imaging of dislocations in SiC using monochromatic synchrotron topography

X. R. Huang, D. R. Black, A. T. Macrander, J. Maj, Y. Chen, and M. Dudley

Appl. Phys. Lett. 91, 231903 (2007); http://dx.doi.org/10.1063/1.2814032 (3 pages) | Cited 5 times

Online Publication Date: 4 December 2007

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We demonstrate high-geometrical-resolution imaging of dislocations in 4H-SiC by monochromatic synchrotron topography (but still under the “integrated wave” condition). In back-reflection topographs, 1c screw dislocation images are “magnified” to appear as well-defined circular white spots, while basal plane dislocations with opposite edge Burgers vector components exhibit two distinct kinds of contrast features. All the dislocation images are precisely described by ray-tracing simulations. This imaging technique provides an accurate, comprehensive, and nondestructive characterization tool, which is needed by current SiC researchers is used for industrial applications. It also provides a simple picture for understanding the mechanisms underlying synchrotron diffraction imaging of defects.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Mm Grain and twin boundaries
61.72.Nn Stacking faults and other planar or extended defects
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