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12 Mar 2007

Volume 90, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 90, 113108 (2007); http://dx.doi.org/10.1063/1.2714186 (3 pages)

Samuel L. Mensah, Vijaya K. Kayastha, Ilia N. Ivanov, David B. Geohegan, and Yoke Khin Yap
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Selectively coated photonic crystal fiber for highly sensitive fluorescence detection

Stephan Smolka, Michael Barth, and Oliver Benson

Appl. Phys. Lett. 90, 111101 (2007); http://dx.doi.org/10.1063/1.2713132 (3 pages) | Cited 12 times

Online Publication Date: 12 March 2007

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The authors investigate the potential of hollow core photonic crystal fibers (HCPCFs) for highly sensitive fluorescence detection by selectively coating the central hole of a HCPCF with fluorophores. After studying the influence of reabsorption and intermolecular effects on the emission, they show that dye concentrations down to 10−9M can be detected using only nanoliter sample volumes. The results indicate that HCPCF are well suited for sensing applications involving internal emission or scattering processes, such as fluorescence based gas sensing or surface-enhanced Raman scattering, and may be integrated into compact optical devices.
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42.81.Pa Sensors, gyros
42.70.Qs Photonic bandgap materials
07.60.Vg Fiber-optic instruments
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.Gk Analytical methods involving vibrational spectroscopy

Low threshold current density and negative characteristic temperature 1.3 μm InAs self-assembled quantum dot lasers

T. J. Badcock, R. J. Royce, D. J. Mowbray, M. S. Skolnick, H. Y. Liu, M. Hopkinson, K. M. Groom, and Q. Jiang

Appl. Phys. Lett. 90, 111102 (2007); http://dx.doi.org/10.1063/1.2713136 (3 pages) | Cited 19 times

Online Publication Date: 12 March 2007

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By combining optimized growth of the GaAs spacer layers and p-type modulation doping of the quantum dots, a 1.3 μm emitting self-assembled quantum dot laser exhibiting both a low threshold current density and negative-T0 temperature behavior at room temperature is achieved. Spontaneous emission measurements provide no evidence for enhanced Auger recombination in doped devices. The negative T0 exhibited by the doped device is consistent with a delayed thermalization of carriers within the quantum dot ensemble.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Observation of the splitting of degenerate surface plasmon polariton modes in a two-dimensional metallic nanohole array

Lin Pang, Kevin A. Tetz, and Yeshaiahu Fainman

Appl. Phys. Lett. 90, 111103 (2007); http://dx.doi.org/10.1063/1.2713145 (3 pages) | Cited 12 times

Online Publication Date: 12 March 2007

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The authors report the experimental observation of the splitting of the degenerate (0,±1) surface plasmon polariton modes excited in a metallic nanohole array integrated with microfluidic channel for delivery and precise control of the index of refraction of overlaying layer. They use high-resolution wavelength and angle scans for excitation of the surface modes and a polarizer-analyzer pair to suppress the nonresonant transmission. The two resultant modes include an intense, spectrally broad low-energy mode and a weaker, much narrower bandwidth high-energy mode.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
73.22.Lp Collective excitations
78.68.+m Optical properties of surfaces
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)

Enhancement of six-wave mixing by atomic coherence in a four-level inverted Y system

Yanpeng Zhang and Min Xiao

Appl. Phys. Lett. 90, 111104 (2007); http://dx.doi.org/10.1063/1.2713868 (3 pages) | Cited 24 times

Online Publication Date: 12 March 2007

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The authors have considered the coexisting dressed four-wave mixing (FWM) and six-wave mixing (SWM) in an open four-level inverted Y configuration. The authors also report an experimental observation of optical pumping-assisted FWM and electromagnetically induced transparency (EIT)-assisted SWM. The efficient SWM can be selected by EIT window and controlled by the coupling as well as dressed field detuning and power. Due to EIT and optical pumping assistance, the enhanced SWM signal is more than ten times lager than the coexisting FWM signal.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
32.80.Xx Level crossing and optical pumping

High-efficiency switchable flat diffractive ophthalmic lens with three-layer electrode pattern and two-layer via structures

Guoqiang Li, Pouria Valley, Pekka Äyräs, David L. Mathine, Seppo Honkanen, and N. Peyghambarian

Appl. Phys. Lett. 90, 111105 (2007); http://dx.doi.org/10.1063/1.2712773 (3 pages) | Cited 9 times

Online Publication Date: 13 March 2007

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A general design for switchable, flat, liquid crystal diffractive lens with three-layer electrode pattern and two-layer via structures is reported for near-, intermediate-, and distance-vision corrections of presbyopic eyes. The microfabricated transparent concentric ring electrodes are distributed in two layers and different voltages are applied to each electrode through bus lines in another layer. Connection between the electrodes and the bus lines is achieved by vias (conducting holes for vertical interconnections) in the third dimension. For demonstration, a lens is first tuned with a focal length of 1 m (1 diopter add power), eight-level phase modulation, and diffraction efficiency above 92% and then reconfigured to operate as a 2 diopter four-level lens with a diffraction efficiency of 78%. The lens operates with low voltages and a rise time of 150 ms. This design methodology allows the aperture needed for practical use and a power-failure-safe configuration.
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42.79.Bh Lenses, prisms and mirrors
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.70.Df Liquid crystals
42.15.Eq Optical system design
42.66.Ct Anatomy and optics of eye

Image enhanced polymer-based multimode interference coupler covering C and L bands using deeply etched air trenches

Xiaolong Wang and Ray T. Chen

Appl. Phys. Lett. 90, 111106 (2007); http://dx.doi.org/10.1063/1.2713626 (3 pages) | Cited 1 time

Online Publication Date: 13 March 2007

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A design of multimode interference coupler with deeply etched air trenches at the boundary of the multimode section is proposed for photonic integrated circuitry on low-index-contrast materials. The device length decreases from 820 to 750 μm for a 1×8 polymer multimode interference coupler. Due to the enhanced optical confinement, the optimized coupler with air trenches experimentally achieved 0.28/0.23 dB reduced insertion loss, 2.16/2.34 dB improved contrast ratio for transverse-electric and transverse-magnetic polarization, compared with conventional multimode interference coupler. The device entirely covers the wavelength range of both C and L bands, which is sufficient for broadband communications.
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42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
42.70.Jk Polymers and organics
42.82.Bq Design and performance testing of integrated-optical systems
42.15.Eq Optical system design

Practicable enhancement of spontaneous emission using surface plasmons

Greg Sun, Jacob B. Khurgin, and Richard A. Soref

Appl. Phys. Lett. 90, 111107 (2007); http://dx.doi.org/10.1063/1.2539745 (3 pages) | Cited 49 times

Online Publication Date: 14 March 2007

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The authors develop a rigorous theory of the enhancement of spontaneous emission from a light emitting device via coupling the radiant energy in and out of surface plasmon polaritons (SPPs) on the metal-dielectric interface. Using the GaN/Ag system as an example, the authors show that using SPP pays off only for emitters that have a low luminescence efficiency.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.55.Hx Other solid inorganic materials
78.68.+m Optical properties of surfaces
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)

Integrated waveguide with a microfluidic channel in spiral geometry for spectroscopic applications

Linan Jiang and Stanley Pau

Appl. Phys. Lett. 90, 111108 (2007); http://dx.doi.org/10.1063/1.2713356 (3 pages) | Cited 9 times

Online Publication Date: 14 March 2007

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The authors fabricated and tested a compact optical sensor with an integrated waveguide and a microchannel in spiral geometry. The multimode waveguide, consisting of an SU-8 core of 40 μm thick and 50 μm wide and a fluid cladding layer of 60 μm thick, realizes a light-fluid interaction length of 110 mm within a device area of 4 cm2. The waveguide sensor measures changes in liquid sample concentration and is sensitive to changes in liquid refractive index. Absorbance measurements using the spiral waveguide sensor demonstrate increased sensitivity compared with a linear geometry sensor.
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42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
47.85.Np Fluidics
82.80.-d Chemical analysis and related physical methods of analysis

GaSb homojunctions for far-infrared (terahertz) detection

P. V. V. Jayaweera, S. G. Matsik, A. G. U. Perera, Y. Paltiel, Ariel Sher, Arie Raizman, H. Luo, and H. C. Liu

Appl. Phys. Lett. 90, 111109 (2007); http://dx.doi.org/10.1063/1.2713760 (3 pages) | Cited 7 times

Online Publication Date: 14 March 2007

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A GaSb based homojunction interfacial work function internal photoemission far-infrared (>30 μm) detector is presented. Metal-organic vapor phase epitaxy grown p-GaSb/GaSb samples show 9.7 A/W peak responsivity and a peak detectivity of 5.7×1011 Jones with effective quantum efficiency of 33% at 36 μm and 4.9 K. The detector exhibits a 97 μm ( ∼ 3 THz) free carrier response threshold wavelength. Results indicate that p-GaSb homojunction internal work function internal photoemission detectors are promising candidates to be a competitor for terahertz applications.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Effects of morphology and optical contrast in organic distributed feedback lasers

M. Salerno, G. Gigli, M. Zavelani-Rossi, S. Perissinotto, and G. Lanzani

Appl. Phys. Lett. 90, 111110 (2007); http://dx.doi.org/10.1063/1.2713762 (3 pages) | Cited 11 times

Online Publication Date: 14 March 2007

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Optically pumped organic distributed feedback lasers, based on the same cavity geometry and polymeric active material, but patterned with different methods, are compared. In one case, the pattern is transferred into the polymer by spin coating the latter on top of a silica master. In the other case, the master is used as a mold to imprint a polymer film. The comparison shows that the imprinted structures, even though a lower quality copy of the master at morphological level, exhibit better performance. This result is checked for different laser cavities, and a qualitative explanation in terms of optical contrast is provided.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Excimer laser annealing of silicon nanowires

Nipun Misra, Li Xu, Yaoling Pan, Nathan Cheung, and Costas P. Grigoropoulos

Appl. Phys. Lett. 90, 111111 (2007); http://dx.doi.org/10.1063/1.2713774 (3 pages) | Cited 6 times

Online Publication Date: 14 March 2007

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Nanowires can potentially be used with low-cost flexible plastic substrates for applications such as large-area displays and sensor arrays. However, high temperature processing steps such as thermal annealing that are incompatible with plastic substrates are still a major hindrance. Laser annealing permits localized energy input without affecting the underlying substrate and can help overcome this problem. In this study, the excimer laser annealing of silicon nanowires is demonstrated to be an efficient means of activating implanted dopants. The optical absorption of the nanowires is discussed and the effect of parameters such as fluence and number of pulses is investigated.
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61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.67.Lt Quantum wires

(In,Ga)N/GaN microcavities with double dielectric mirrors fabricated by selective removal of an (Al,In)N sacrificial layer

F. Rizzi, P. R. Edwards, K. Bejtka, F. Semond, X. N. Kang, G. Y. Zhang, E. Gu, M. D. Dawson, I. M. Watson, and R. W. Martin

Appl. Phys. Lett. 90, 111112 (2007); http://dx.doi.org/10.1063/1.2712786 (3 pages) | Cited 8 times

Online Publication Date: 15 March 2007

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Comparable microcavities with 3λ/2 ( ∼ 240 nm) active regions containing distributed (In,Ga)N quantum wells, grown on GaN substrates and bounded by two dielectric mirrors, have been fabricated by two different routes: one using laser lift-off to process structures grown on GaN-on-sapphire templates and the second using freestanding GaN substrates, which are initially processed by mechanical thinning. Both exploit the properties of an Al0.83In0.17N layer, lattice matched to the GaN substrate and spacer layers. In both cases cavity quality factors >400 are demonstrated by measurements of the cavity-filtered room-temperature excitonic emission near 410 nm.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.79.Bh Lenses, prisms and mirrors
42.82.Cr Fabrication techniques; lithography, pattern transfer

Electron capture acceleration channel in a slit laser beam

P. X. Wang, W. Scheid, and Y. K. Ho

Appl. Phys. Lett. 90, 111113 (2007); http://dx.doi.org/10.1063/1.2713168 (3 pages) | Cited 5 times

Online Publication Date: 15 March 2007

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Using numerical simulations, the authors find that the electrons can be captured and accelerated to high energies (GeV) in a slit laser beam with an intensity of Iλ2 ∼ 1020 W/cm2 μm2, where λ is the laser wavelength in units of μm. The range of the optimum incident energy is very wide, even up to GeV. These results are of interest for experiments because the relatively low intensity can be achieved with present chirped pulse amplification technique and a wide range of incident energies means that a multistage acceleration is possible.
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41.75.Jv Laser-driven acceleration
42.62.-b Laser applications

Organic light-emitting diodes with photonic crystals on glass substrate fabricated by nanoimprint lithography

Kuniaki Ishihara, Masayuki Fujita, Ippei Matsubara, Takashi Asano, Susumu Noda, Hiroshi Ohata, Akira Hirasawa, Hiroshi Nakada, and Noriyuki Shimoji

Appl. Phys. Lett. 90, 111114 (2007); http://dx.doi.org/10.1063/1.2713237 (3 pages) | Cited 42 times

Online Publication Date: 15 March 2007

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The authors have fabricated organic light-emitting diodes (OLEDs) having two-dimensional photonic crystals (PC) as light extraction elements by employing nanoimprint lithography technique. PCs were imprinted on the glass substrate and OLED layers were formed on the imprinted side of the glass substrate. The device having PC showed the improvement of luminance by a factor of 1.5 compared to normal devices. The authors conclude that the nanoimprint lithography is very useful for the fabrication of the OLEDs with PC.
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85.60.Jb Light-emitting devices
85.40.Hp Lithography, masks and pattern transfer

Refractive femtosecond laser beam shaping for two-photon polymerization

R. J. Winfield, B. Bhuian, S. O’Brien, and G. M. Crean

Appl. Phys. Lett. 90, 111115 (2007); http://dx.doi.org/10.1063/1.2713787 (3 pages) | Cited 2 times

Online Publication Date: 15 March 2007

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Three dimensional microstructure fabrication by two-photon polymerization is an established technique that normally uses single beam serial writing. Recently the use of a micro-optical element, to give multipoint beam delivery, was reported to give a degree of parallel processing. The authors describe an alternative approach to parallel processing using an axicon lens. This is a refractive element that, in combination with a high power microscope objective, efficiently transforms the laser beam from a Gaussian spot to an annulus. The authors demonstrate that the beam can polymerize a three dimensional shape, with nanoscale resolution. The use of more sophisticated refractive beam shaping is also discussed.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.79.Bh Lenses, prisms and mirrors
42.62.-b Laser applications
82.35.-x Polymers: properties; reactions; polymerization

Ultraviolet light-emitting diodes with self-assembled InGaN quantum dots

Il-Kyu Park, Min-Ki Kwon, Seong-Bum Seo, Ja-Yeon Kim, Jae-Hong Lim, and Seong-Ju Park

Appl. Phys. Lett. 90, 111116 (2007); http://dx.doi.org/10.1063/1.2712804 (3 pages) | Cited 15 times

Online Publication Date: 16 March 2007

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A photoluminescence study showed that the self-assembled InGaN quantum dots (QDs) provide strongly localized recombination sites for carriers and that the piezoelectric field-induced quantum-confined Stark effect (QCSE) is small because the height of QDs is too small to separate the wave functions of electrons and holes. The InGaN QD light-emitting diode (LED) showed an emission peak at 400 nm, and the peak was redshifted with increasing injection current, indicating a small QCSE. The light output power of an InGaN QD LED increased linearly with increasing injection current due to the strongly localized recombination sites of the InGaN QDs.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Weak coupling interactions of colloidal lead sulphide nanocrystals with silicon photonic crystal nanocavities near 1.55 μm at room temperature

Ranojoy Bose, Xiaodong Yang, Rohit Chatterjee, Jie Gao, and Chee Wei Wong

Appl. Phys. Lett. 90, 111117 (2007); http://dx.doi.org/10.1063/1.2714097 (3 pages) | Cited 23 times

Online Publication Date: 16 March 2007

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The authors observe the weak coupling of lead sulphide nanocrystals to localized defect modes of two-dimensional silicon nanocavities. Cavity resonances characterized with ensemble nanocrystals are verified with cold-cavity measurements using integrated waveguides. Polarization dependence of the cavity field modes is observed. The linewidths measured in coupling experiments are broadened in comparison to the cold-cavity characterization, partly due to large homogeneous linewidths of the nanocrystals. The calculated Purcell factor [Phys. Rev. 69, 681 (1946)] for a single exciton is 100, showing promise toward applications in single photon systems. These novel light sources operate near 1.55 μm wavelengths at room temperature, permitting integration with current fiber communication networks.
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42.70.Qs Photonic bandgap materials
71.35.-y Excitons and related phenomena

InAs/AlSb quantum cascade lasers emitting below 3 μm

J. Devenson, R. Teissier, O. Cathabard, and A. N. Baranov

Appl. Phys. Lett. 90, 111118 (2007); http://dx.doi.org/10.1063/1.2714098 (3 pages) | Cited 40 times

Online Publication Date: 16 March 2007

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Quantum cascade lasers emitting below 3 μm are demonstrated. The lasers based on the InAs/AlSb material system emit at 2.95–2.97 μm in pulsed mode with threshold current densities near 3 kA/cm2 at 84 K and operate up to room temperature. No degradation has been observed in laser performances compared with InAs/AlSb quantum cascade lasers emitting at 3.14–3.35 μm. The obtained results show no influence of the L valley in InAs on operation of these short wavelength quantum cascade lasers.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Visible submicron microdisk lasers

Zhaoyu Zhang, Lan Yang, Victor Liu, Ting Hong, Kerry Vahala, and Axel Scherer

Appl. Phys. Lett. 90, 111119 (2007); http://dx.doi.org/10.1063/1.2714312 (3 pages) | Cited 30 times

Online Publication Date: 16 March 2007

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The authors describe the performance of submicron microdisk lasers fabricated within InGaP/InGaAlP quantum well material working at room temperature. The smallest lasers, with diameters of approximately 600 nm, feature ultrasmall mode volumes and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 μm3 enable microdisk lasers to be used as spectroscopic sources. Here the authors demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron microdisk lasers.
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42.55.Sa Microcavity and microdisk lasers
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
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Ultrafast plasma shutter for shielding high-energy ions from a laser-produced plasma

H. Yashiro and T. Tomie

Appl. Phys. Lett. 90, 111501 (2007); http://dx.doi.org/10.1063/1.2714095 (3 pages)

Online Publication Date: 12 March 2007

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A laser-produced plasma was employed as an ultrafast shutter for shielding high-energy ions. Fast ions with energy on the order of keV were prevented from reaching the detector by a shutter plasma. The ion signal was suppressed to 1% of the unshielded peak ion signal. Suppression of the ion signal was observed up to 10 mm from the target surface of the shutter plasma. The shutter closing time was 40 ns at the distance of 2 mm. The plasma shutter could operate even at a 100 kHz repetition rate. The high-density plasma acts as a shutter by capturing a low-density plasma.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Radio-frequency dielectric-barrier glow discharges in atmospheric argon

J. J. Shi and M. G. Kong

Appl. Phys. Lett. 90, 111502 (2007); http://dx.doi.org/10.1063/1.2713141 (3 pages) | Cited 12 times

Online Publication Date: 15 March 2007

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In this letter, an experimental investigation is presented to characterize the properties and benefits of radio-frequency (rf) dielectric-barrier discharges (DBDs) in atmospheric argon. Compared to rf atmospheric glow discharges generated with bare electrodes, atmospheric argon rf DBDs are shown to remain stable and uniform over a large current range from the α and the γ modes. Optical emission spectroscopy is used to show an active underpinning plasma chemistry and a gas temperature range of 461–562 K. These highlight the advantages of argon rf DBD as a surface processing technique over more expensive helium-based rf atmospheric glow discharges.
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52.80.Pi High-frequency and RF discharges
52.80.Hc Glow; corona
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)

Observation of temporal behavior of the emission frequency from an ultrashort, high-power, and compact millimeter-wave source

Takeshi Higashiguchi, Nobuo Ohata, Kun Li, and Noboru Yugami

Appl. Phys. Lett. 90, 111503 (2007); http://dx.doi.org/10.1063/1.2713130 (3 pages) | Cited 3 times

Online Publication Date: 16 March 2007

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The authors demonstrated observation of emission frequency chirping of millimeter-wave emission from a time-varying plasma produced by a nanosecond UV laser pulse. By using a heterodyne interferometer the time-resolved frequency of the emission from a dc to ac radiation converter source was observed to range from 20 to 32 GHz due to the rapid plasma creation. This chirped pulse is suitable for application in various novel dense plasma diagnostics.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Dg Plasma sources
52.70.Gw Radio-frequency and microwave measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Effect of enhanced C2 growth chemistry on nanodiamond film deposition

Kungen Teii and Tomohiro Ikeda

Appl. Phys. Lett. 90, 111504 (2007); http://dx.doi.org/10.1063/1.2713334 (3 pages) | Cited 13 times

Online Publication Date: 16 March 2007

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A route to high-purity nanocrystalline diamond films from C2 dimers and related mechanisms have been investigated by enhancing C2 growth chemistry in Ar-rich microwave plasmas. Efficient C2 production by direct dissociation from acetylene causes the micro- to nanocrystal transition with a low threshold Ar concentration of ∼ 70% and produces films of ∼ 20 nm grains with a distinct visible-Raman peak of diamond. C2 grows nanodiamond on diamond surfaces but rarely initiates nucleation on foreign surfaces. The phase purity can be improved by increasing the dominance of nanodiamond growth from C2 over nondiamond growth from CHx(x = 0–3) and large radicals.
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81.05.Cy Elemental semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.07.Bc Nanocrystalline materials
52.77.Dq Plasma-based ion implantation and deposition
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
78.66.Db Elemental semiconductors and insulators
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Core structures of the a-edge dislocation in InN

H. P. Lei, P. Ruterana, G. Nouet, X. Y. Jiang, and J. Chen

Appl. Phys. Lett. 90, 111901 (2007); http://dx.doi.org/10.1063/1.2712799 (3 pages) | Cited 6 times

Online Publication Date: 12 March 2007

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Stillinger-Weber potential parameters were optimized for InN by fitting to the bulk material properties and point defect energy in order to calculate the core structure of the a-edge dislocation. The initial displacement field is imposed in the perfect crystal according to isotropic linear elasticity theory, and then the system is relaxed to the minimum energy. The different origins of the displacement field generate three cores with four, eight or five/seven atoms. The calculated energies indicate that the four-atom core structure is the most stable for InN.
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61.72.J- Point defects and defect clusters
61.72.Bb Theories and models of crystal defects
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Screening the built-in electric field in 4H silicon carbide stacking faults

S. Juillaguet, J. Camassel, M. Albrecht, and T. Chassagne

Appl. Phys. Lett. 90, 111902 (2007); http://dx.doi.org/10.1063/1.2713169 (3 pages) | Cited 6 times

Online Publication Date: 12 March 2007

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The authors report a detailed comparison of low temperature photoluminescence (LTPL) and cathodo luminescence (LTCL) spectra collected in the same stacking faults rich area of a 4H silicon carbide epitaxial layer. In both cases, they find that the maximum wavelength of the defect-related emission lines shifts when the excitation spot position moves across the defect zone. The shift is excitation-intensity dependent. It is very small for LTPL (4 meV) but reach 20 meV for LTCL. This constitutes the first experimental evidence that a screening of the quantum confined Stark effect can be achieved in 4H-SiC SF quantum wells.
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78.66.Nk Insulators
78.55.Hx Other solid inorganic materials
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.Nn Stacking faults and other planar or extended defects
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