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14 Dec 2009

Volume 95, Issue 24, Articles (24xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 95, 242102 (2009); http://dx.doi.org/10.1063/1.3272858 (3 pages)

W. H. Lim, F. A. Zwanenburg, H. Huebl, M. Möttönen, K. W. Chan, A. Morello, and A. S. Dzurak
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Stimulated emission of near-infrared radiation by current injection into silicon (100) quantum well

S. Saito, Y. Suwa, H. Arimoto, N. Sakuma, D. Hisamoto, H. Uchiyama, J. Yamamoto, T. Sakamizu, T. Mine, S. Kimura, T. Sugawara, and M. Aoki

Appl. Phys. Lett. 95, 241101 (2009); http://dx.doi.org/10.1063/1.3273367 (3 pages) | Cited 6 times

Online Publication Date: 14 December 2009

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We describe the observation of stimulated emissions by current injections into a silicon quantum well. The device consists of a free standing membrane with a distributed feedback resonant cavity fabricated by state-of-the-art silicon processes. The emission spectra have multimode structures peaked in the near-infrared region above the submilliampere threshold currents at room temperatures. Consequently, electronics and photonics should be able to be converged on chips by using silicon quantum well laser diodes.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Fabrication of high efficiency III-V quantum nanostructures at low thermal budget on Si

S. Bietti, C. Somaschini, S. Sanguinetti, N. Koguchi, G. Isella, and D. Chrastina

Appl. Phys. Lett. 95, 241102 (2009); http://dx.doi.org/10.1063/1.3273860 (3 pages) | Cited 8 times

Online Publication Date: 14 December 2009

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We fabricate high efficiency GaAs/AlGaAs quantum nanostructure active layer for intersubband detectors and light emitting devices on a silicon substrate. The whole process of formation of the GaAs/AlGaAs active layer was realized via droplet epitaxy and migration enhanced epitaxy maintaining the growth temperature ⩽ 350 °C, thus resulting in a low thermal budget procedure compatible with back-end integration of the fabricated materials on integrated circuits. The realized quantum nanostructures show optical efficiencies comparable to those achievable with state of the art quantum dot materials grown on GaAs substrates.
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81.16.-c Methods of micro- and nanofabrication and processing
85.60.Jb Light-emitting devices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors
85.40.Sz Deposition technology

Thermal emission from finite photonic crystals

Christian J. Schuler, Christian Wolff, Kurt Busch, and Marian Florescu

Appl. Phys. Lett. 95, 241103 (2009); http://dx.doi.org/10.1063/1.3275578 (3 pages) | Cited 2 times

Online Publication Date: 16 December 2009

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We present a microscopic theory of thermal emission from finite-sized photonic crystals and show that the directional spectral emissivity and related quantities can be evaluated via standard bandstructure computations without any approximation. We then identify the physical mechanisms through which interfaces modify the potentially super-Planckian radiation flow inside infinite photonic crystals, such that thermal emission from finite-sized samples is consistent with the fundamental limits set by Planck’s law. As an application, we further demonstrate that a judicious choice of a photonic crystal’s surface termination facilitates considerable control over both the spectral and angular thermal emission properties.
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78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.60.Kn Thermoluminescence

Spin-dependent photoconductivity in nonmagnetic semiconductors at room temperature

F. Zhao, A. Balocchi, A. Kunold, J. Carrey, H. Carrère, T. Amand, N. Ben Abdallah, J. C. Harmand, and X. Marie

Appl. Phys. Lett. 95, 241104 (2009); http://dx.doi.org/10.1063/1.3273393 (3 pages) | Cited 3 times

Online Publication Date: 16 December 2009

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By combining optical spin injection techniques with transport spectroscopy tools, we demonstrate a spin-photodetector allowing for the electrical measurement and active filtering of conduction band electron spin at room temperature in a simple nonmagnetic GaAsN semiconductor structure. By switching the polarization of the incident light from linear to circular, we observe a spin dependent photoconductivity change reaching up to 40% without the need of an external magnetic field. The spin dependent photoconductivity change relies on the efficient spin filtering effect of conduction band electrons on N-induced Ga self-interstitial deep paramagnetic centers.
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72.40.+w Photoconduction and photovoltaic effects
72.25.Dc Spin polarized transport in semiconductors
61.72.jj Interstitials
71.20.Nr Semiconductor compounds

Subwavelength direct laser writing by strong optical nonlinear absorption and melt-ablation threshold characteristics

Jingsong Wei, Jing Liu, and Xinbing Jiao

Appl. Phys. Lett. 95, 241105 (2009); http://dx.doi.org/10.1063/1.3272011 (3 pages) | Cited 5 times

Online Publication Date: 16 December 2009

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In this work, we propose nonlinear absorption and melt-ablation threshold characteristics induced subwavelength direct laser writing. The writing materials need to have two features: one is strong nonlinear absorption, and the other is melt-ablation threshold characteristics. According to the strong nonlinear absorption and melt-ablation threshold characteristics of AgInSbTe thin films, the effective energy absorption spot is calculated. The results indicate that the full width at half maximum of the effective energy absorption spot is about 2/5 the original spot. If only the energy intensity above 80% maximum can induce the melt-ablation, the direct laser writing mark size or linewidth can be reduced to 0.14λ/NA (NA denotes numerical aperture), which is only about 0.115 times the original spot size. The calculated results are verified, where the mark size is reduced to about 1/8 the real spot.
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42.62.Cf Industrial applications
42.79.Wc Optical coatings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.65.-k Nonlinear optics

Photocurrent in Ag–Si photodiodes modulated by plasmonic nanopatterns

Yumin Wang, Xiaodong Su, Yongyuan Zhu, Qianjin Wang, Dongliang Zhu, Junwei Zhao, San Chen, Wanxia Huang, and Shan Wu

Appl. Phys. Lett. 95, 241106 (2009); http://dx.doi.org/10.1063/1.3275708 (3 pages) | Cited 5 times

Online Publication Date: 18 December 2009

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We demonstrate that Ag–Si photodiodes allow photocurrents to be modulated by changing periods of nanopatterns on Ag film. The maximum and minimum photocurrents occur in certain periods corresponding to the excitation of surface plasmon polariton and Wood’s anomaly, which can be predicted with the help of related theories. Therefore, it is feasible to design nanopatterns to satisfy special requirements.
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85.60.Dw Photodiodes; phototransistors; photoresistors

Mid-infrared PbTe vertical external cavity surface emitting laser on Si-substrate with above 1 W output power

M. Rahim, M. Fill, F. Felder, D. Chappuis, M. Corda, and H. Zogg

Appl. Phys. Lett. 95, 241107 (2009); http://dx.doi.org/10.1063/1.3275792 (3 pages) | Cited 7 times

Online Publication Date: 18 December 2009

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Mid-infrared vertical external cavity surface emitting lasers (VECSELs) emitting above 1 W output power in pulsed mode and up to 17 mW in continuous mode at −172 °C were realized. Emission wavelength changes from 5 μm at −172 °C to 3.6 μm at 20 °C heat sink temperature. The active medium is a one wavelength thick PbTe layer grown by molecular beam epitaxy on a Si-substrate. It is followed by a 2.5 pair Pb1−yEuyTe/EuTe epitaxial Bragg mirror. The cavity is completed with an external curved Pb1−yEuyTe/BaF2 mirror. The VECSEL is optically pumped with 1.55 μm wavelength laser and In-soldered to Cu heat sink. No microstructural processing is needed.
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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

Reconfigurable liquid crystal droplets using a dielectric force

Hongwen Ren, Seung Hee Lee, and Shin Tson Wu

Appl. Phys. Lett. 95, 241108 (2009); http://dx.doi.org/10.1063/1.3275795 (3 pages) | Cited 1 time

Online Publication Date: 18 December 2009

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Dielectric force-induced shape change of liquid crystal (LC) droplets which are randomly dispersed in a liquid polymer is demonstrated. By applying a sufficiently high voltage, the isolated spherical LC droplets are coalesced to form a planar layer, while the cylindrical LC droplets which make contact on both substrate surfaces cannot be deformed easily. On the contrary, each cylindrical LC droplet functions as a swollen well to unite the adjacent LC droplets. The dynamic behavior for flattening the spherical LC droplets is also studied. Potential applications of these reconfigurable LC droplets for various photonic devices are discussed.
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61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems
68.15.+e Liquid thin films
77.22.Ch Permittivity (dielectric function)

Improved performance of GaN-based blue light emitting diodes with InGaN/GaN multilayer barriers

Hun Jae Chung, Rak Jun Choi, Min Ho Kim, Jae Woong Han, Young Min Park, Yu Seung Kim, Ho Sun Paek, Cheol Soo Sone, Yong Jo Park, Jong Kyu Kim, and E. Fred Schubert

Appl. Phys. Lett. 95, 241109 (2009); http://dx.doi.org/10.1063/1.3276066 (3 pages) | Cited 11 times

Online Publication Date: 18 December 2009

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Multi-layer barrier structure is suggested as an alternative approach to single-layer polarization matching barrier structure for the reduction of efficiency droop. Time resolved photoluminescence measurement showed that polarization field was reduced by 19% in the multilayer barrier light emitting diodes structures. Optical power measurements on packaged devices showed overall increase of external quantum efficiency for all currents up to the current density of 150 A/cm2. Increase of optical power is attributed to reduced polarization and decreased current overflow to p-side cladding layers. These results provide additional evidences that polarization is important in addressing the droop problem.
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85.60.Jb Light-emitting devices
85.30.De Semiconductor-device characterization, design, and modeling
78.55.Cr III-V semiconductors

Whispering gallery-mode lasing in ZnO microrods at room temperature

J. Dai, C. X. XU, K. Zheng, C. G. Lv, and Y. P. Cui

Appl. Phys. Lett. 95, 241110 (2009); http://dx.doi.org/10.1063/1.3276069 (3 pages) | Cited 15 times

Online Publication Date: 18 December 2009

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An individual hexagonal ZnO microrod was employed as a whispering-gallery mode (WGM) microcavity to obtain ultraviolet lasing at room temperature. The WGM lasing shows a low threshold, a high quality factor, and distinct mode structure. A typical stimulated emission from the ZnO microrod with diagonal of 6.67 μm exhibits a low lasing threshold of 255 kW/cm2. The observed discrete lasing modes match with the simulated positions very well. The spatial distribution of the lasing intensity demonstrates the lasing output direction and provides the direct evidence of the WGM resonant mechanism. We systematically investigated the lasing performance for different sized microrods.
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78.40.Fy Semiconductors

Dual band terahertz metamaterial absorber: Design, fabrication, and characterization

Qi-Ye Wen, Huai-Wu Zhang, Yun-Song Xie, Qing-Hui Yang, and Ying-Li Liu

Appl. Phys. Lett. 95, 241111 (2009); http://dx.doi.org/10.1063/1.3276072 (3 pages) | Cited 43 times

Online Publication Date: 18 December 2009

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We report the design, simulation, and measurement of a dual-band metamaterial absorber in the terahertz region. Theoretical and experimental results show that the absorber has two distinct and strong absorption points near 0.45 and 0.92 THz, both which are related to the LC resonance of the metamaterial. The distributions of the power flow and the power loss indicate that the absorber is an excellent electromagnetic wave collector: the wave is first trapped and reinforced in certain specific locations and then completely consumed. This dual-band absorber has applications in many scientific and technological areas.
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42.70.-a Optical materials
42.79.-e Optical elements, devices, and systems
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The effect of hydrogen charging on Ln-based amorphous materials

C. P. Chuang, J. H. Huang, W. Dmowski, P. K. Liaw, R. Li, T. Zhang, and Y. Ren

Appl. Phys. Lett. 95, 241901 (2009); http://dx.doi.org/10.1063/1.3266521 (3 pages) | Cited 2 times

Online Publication Date: 14 December 2009

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In present work, the effects of hydrogen charging on Ln-based (Ln = La,Ce) bulk-metallic glasses (BMG) are studied. The (La0.5Ce0.5)65Al10Co25 were charged with hydrogen by an electrochemical method in an alkali solution. The hydrogen concentration in the sample after a 36 h charge can reach as high as 1286 w-ppm. With the presence of hydrogen atoms, the hardness of specimen increased by 80% compared to the as-cast samples. The structural evolution of the amorphous matrix due to the hydrogen-uptake process was investigated by the high-energy x-ray scattering technique. The sample surface was crystallized after hydrogen charging. X-ray diffraction measurements revealed broad crystalline peaks superimposed on an amorphous-scattering pattern. The crystalline phase grew from the surface to at least one hundred microns deep into the amorphous matrix. The atomic arrangements of both amorphous and crystalline phases were characterized by the atomic pair-distribution function.
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82.80.Fk Electrochemical methods
61.43.Fs Glasses
62.20.Qp Friction, tribology, and hardness
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.

Liquid Ge2Sb2Te5 studied by extended x-ray absorption

A. V. Kolobov, P. Fons, M. Krbal, R. E. Simpson, S. Hosokawa, T. Uruga, H. Tanida, and J. Tominaga

Appl. Phys. Lett. 95, 241902 (2009); http://dx.doi.org/10.1063/1.3272680 (3 pages) | Cited 3 times

Online Publication Date: 15 December 2009

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We report on x-ray absorption studies of the structure of the liquid phase of a prototypical phase-change material Ge2Sb2Te5. We demonstrate that the local structure of liquid Ge2Sb2Te5 is very similar to that of amorphous Ge2Sb2Te5. Ge atoms in the liquid phase are found to be covalently bonded suggesting a semiconducting nature of the melt.
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61.25.-f Studies of specific liquid structures
78.70.Dm X-ray absorption spectra

Comprehensive doping and temperature studies of spin relaxation in InSb

D. Guzun, E. A. DeCuir, Jr., Vas. P. Kunets, Yu. I. Mazur, G. J. Salamo, S. Q. Murphy, P. A. R. Dilhani Jayathilaka, T. D. Mishima, and M. B. Santos

Appl. Phys. Lett. 95, 241903 (2009); http://dx.doi.org/10.1063/1.3274040 (3 pages)

Online Publication Date: 15 December 2009

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Time resolved pump-probe measurements of the spin relaxation rate in thick epilayers and bulk InSb have been carried out for a wide range of doping concentrations (intrinsic—2×1018 cm−3) and temperatures (20 to 300 K). Our results are consistent with the dominance of the Elliott–Yafet mechanism across a wide range of carrier concentrations and temperatures for which the electron energy is less than 100 meV.
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73.61.Ey III-V semiconductors
61.72.uj III-V and II-VI semiconductors
78.47.D- Time resolved spectroscopy (>1 psec)
73.50.Dn Low-field transport and mobility; piezoresistance
78.66.Fd III-V semiconductors

Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials

X. J. Wang, Y. Puttisong, C. W. Tu, Aaron J. Ptak, V. K. Kalevich, A. Yu. Egorov, L. Geelhaar, H. Riechert, W. M. Chen, and I. A. Buyanova

Appl. Phys. Lett. 95, 241904 (2009); http://dx.doi.org/10.1063/1.3275703 (3 pages) | Cited 11 times

Online Publication Date: 16 December 2009

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Optically detected magnetic resonance measurements are carried out to study formation of Ga interstitial-related defects in Ga(In)NAs alloys. The defects, which are among dominant nonradiative recombination centers that control carrier lifetime in Ga(In)NAs, are unambiguously proven to be common grown-in defects in these alloys independent of the employed growth methods. The defects formation is suggested to become thermodynamically favorable because of the presence of nitrogen, possibly due to local strain compensation.
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76.70.Hb Optically detected magnetic resonance (ODMR)
61.72.jj Interstitials
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.61.Ey III-V semiconductors

Effect of annealing on atomic ordering of amorphous ZrTaTiNbSi alloy

Tsung-Han Yang, Rong-Tang Huang, Cheng-An Wu, Fu-Rong Chen, Jon-Yiew Gan, Jien-Wei Yeh, and Jagdish Narayan

Appl. Phys. Lett. 95, 241905 (2009); http://dx.doi.org/10.1063/1.3273387 (3 pages) | Cited 5 times

Online Publication Date: 16 December 2009

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In this letter, we have reported on initial stages of atomic ordering in ZrTaTiNbSi amorphous films during annealing. The atomic ordering and structure evolution were studied in Zr17Ta16Ti19Nb22Si26 amorphous films as a function of annealing temperature in the temperature range from 473 to 1173 K. Up to annealing temperature of 1173 K, the films retained amorphous structure, but the degree of disorder is increased with the increase in temperature. The formation of Si–M covalent bonds, which contributed to the local atomic arrangement, occurred in the initial stages of ordering. The bonding reactions between Si and other metal species explain the anomalous structural changes which were observed in x-ray diffraction and transmission electron microscopy. We discuss the stages of phase transformation for amorphous films as a function of annealing temperature. From these results, we propose that annealing leads to formation of random Si–M4 tetrahedron, and two observed rings, a first and second in the electron diffraction patterns compared to M–M and Si–M bond length, respectively.
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81.40.Gh Other heat and thermomechanical treatments
68.55.-a Thin film structure and morphology
64.70.kd Metals and alloys
61.43.Fs Glasses
81.15.Cd Deposition by sputtering
81.05.Bx Metals, semimetals, and alloys

Photoluminescence induced by thermal annealing in SrTiO3 thin film

JaeHoon Rho, SeungHun Jang, Young Dong Ko, SeungJin Kang, Dong-Wook Kim, J.-S. Chung, Miyoung Kim, Moonsup Han, and Eunjip Choi

Appl. Phys. Lett. 95, 241906 (2009); http://dx.doi.org/10.1063/1.3275707 (3 pages) | Cited 5 times

Online Publication Date: 17 December 2009

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We have grown SrTiO3 thin films by rf-sputtering and studied its photoluminescence (PL) property after postannealing treatments. While the as-grown film does not show any PL signal, visible frequency PL emissions are induced by high temperature (T>550 °C) annealing. When subsequent low-T (50 °C) and long term (>8 months) annealing was made, the PL-spectra evolved into another pattern in which four distinct luminescence peaks appear simultaneously at λ = 1.8, 2.2, 2.7, and 3.1 eV. We propose that these remarkable room temperature PL effects are due to both metastable and energetically stabilized defect states formed inside the band gap.
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78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
81.40.Gh Other heat and thermomechanical treatments
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
81.15.Cd Deposition by sputtering

MnSe phase segregation during heteroepitaxy of Mn doped Ga2Se3 on Si(001)

T. C. Lovejoy, E. N. Yitamben, S. M. Heald, F. S. Ohuchi, and M. A. Olmstead

Appl. Phys. Lett. 95, 241907 (2009); http://dx.doi.org/10.1063/1.3273858 (3 pages) | Cited 1 time

Online Publication Date: 17 December 2009

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Heteroepitaxial thin films of Mn-doped Ga2Se3 are grown by molecular beam epitaxy on Si(001):As. Mn-doped films are laminar for the first 1–2 nm, after which oriented islands with flat tops are observed by scanning tunneling microscopy. In contrast with the bulk phase diagram, which predicts MnGa2Se4 precipitates, the precipitates are identified by bond length measurements from extended x-ray absorption fine structure as rocksalt MnSe. This difference is attributed to superior lattice matching of MnSe to the substrate, and an epitaxial relationship between the MnSe and Si substrate is inferred.
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64.75.Qr Phase separation and segregation in semiconductors
64.75.St Phase separation and segregation in thin films
68.55.ag Semiconductors
78.70.Dm X-ray absorption spectra
81.05.Hd Other semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Hole-electron electrical coupling in photorefractive materials

Ivan de Oliveira, Renata Montenegro, and Jaime Frejlich

Appl. Phys. Lett. 95, 241908 (2009); http://dx.doi.org/10.1063/1.3272681 (2 pages) | Cited 2 times

Online Publication Date: 18 December 2009

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We describe an improved mathematical model for photorefractive materials exhibiting hole-electron competition where the constants accounting for electrical coupling between holes and electrons are independently adjusted for each one of them. Experimental results from photorefractive titanosillenite crystals with hole-electron competition, and particularly from a vanadium doped sample, are shown to be better described by this modified model than by the classical one already reported in the literature.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.70.Gi Light-sensitive materials
42.70.Ln Holographic recording materials; optical storage media
42.40.Ht Hologram recording and readout methods
42.79.Vb Optical storage systems, optical disks

Observation of hypersonic phononic crystal effects in porous silicon superlattices

L. C. Parsons and G. T. Andrews

Appl. Phys. Lett. 95, 241909 (2009); http://dx.doi.org/10.1063/1.3275742 (3 pages) | Cited 11 times

Online Publication Date: 18 December 2009

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Brillouin light scattering experiments were carried out on porous silicon superlattices with modulation wavelengths in the range 37–167 nm. Phonon frequencies deduced from the Brillouin spectra show good agreement with those obtained from an elastic continuum model for a system with one-dimensional periodicity. Evidence for the existence of a hypersonic phononic bandgap and zone-folded longitudinal acoustic phonons is reported.
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63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
81.05.Cy Elemental semiconductors
73.21.Cd Superlattices
81.05.Rm Porous materials; granular materials
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Effects of nanowire coalescence on their structural and optical properties on a local scale

V. Consonni, M. Knelangen, U. Jahn, A. Trampert, L. Geelhaar, and H. Riechert

Appl. Phys. Lett. 95, 241910 (2009); http://dx.doi.org/10.1063/1.3275793 (3 pages) | Cited 17 times

Online Publication Date: 18 December 2009

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The effects of GaN nanowire coalescence have been investigated on a local scale by combining high-resolution transmission electron microscopy imaging with spatially resolved cathodoluminescence measurements. Coalescence induces the formation of a network of boundary dislocations, above which I1-type basal-plane stacking faults are nucleated. The former contributes to the reduction in the crystalline quality at the bottom of coalesced nanowires while the latter leads to intense excitonic radiative transitions at 3.42 eV in their center. Despite coalescence, the top of coalesced nanowires presents a very high crystalline quality, resulting in strong radiative recombinations of donor bound excitons at 3.47 eV.
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78.67.Uh Nanowires
71.35.-y Excitons and related phenomena
61.72.Nn Stacking faults and other planar or extended defects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.60.Hk Cathodoluminescence, ionoluminescence
61.46.Km Structure of nanowires and nanorods (long, free or loosely attached, quantum wires and quantum rods, but not gate-isolated embedded quantum wires)

High pressure phase transformation in iron under fast compression

Marina Bastea, Sorin Bastea, and Richard Becker

Appl. Phys. Lett. 95, 241911 (2009); http://dx.doi.org/10.1063/1.3275797 (3 pages) | Cited 1 time

Online Publication Date: 18 December 2009

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We observe kinetic features—velocity loops—at the α to ϵ phase transformation of iron, similar with the ones reported when water is frozen into its ice VII phase under comparable experimental conditions. By using a phase nucleation and growth kinetic model with pressure dependent phase interface velocity we find that the thermodynamic path followed by the sample is strongly dependent on the drive conditions and sample characteristics. The velocity loops become broader and shallower at slower compressions, while on faster time–scales, e.g., for laser drivers, the loops form at higher velocities and may eventually disappear.
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62.50.-p High-pressure effects in solids and liquids
64.70.kd Metals and alloys
65.40.G- Other thermodynamical quantities
64.60.qj Studies of nucleation in specific substances
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Metal organic vapor phase epitaxy growth of single crystalline GaN on planar Si(211) substrates

Roghaiyeh Ravash, Jürgen Bläsing, Thomas Hempel, Martin Noltemeyer, Armin Dadgar, Jürgen Christen, and Alois Krost

Appl. Phys. Lett. 95, 242101 (2009); http://dx.doi.org/10.1063/1.3272673 (3 pages) | Cited 5 times

Online Publication Date: 14 December 2009

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We present metal organic vapor phase epitaxy growth of polarization reduced, wurtzitic gallium nitride layers with an 18° inclination of the c-axis to the surface normal on planar Si(211) substrates. The growth of this layer is performed as c-axis oriented growth on the naturally occurring Si(111) planes of the Si(211) substrate. Cathodoluminescence measurements on a ∼ 1.2 μm thick structure reveals that it has a low concentration of basal plane stacking faults and no prismatic stacking fault luminescence.
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68.55.ag Semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Fd III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Observation of the single-electron regime in a highly tunable silicon quantum dot

W. H. Lim, F. A. Zwanenburg, H. Huebl, M. Möttönen, K. W. Chan, A. Morello, and A. S. Dzurak

Appl. Phys. Lett. 95, 242102 (2009); http://dx.doi.org/10.1063/1.3272858 (3 pages) | Cited 19 times

Online Publication Date: 14 December 2009

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We report on low-temperature electronic transport measurements of a silicon metal-oxidesemiconductor quantum dot, with independent gate control of electron densities in the leads and the quantum dot island. This architecture allows the dot energy levels to be probed without affecting the electron density in the leads and vice versa. Appropriate gate biasing enables the dot occupancy to be reduced to the single-electron level, as evidenced by magnetospectroscopy measurements of the ground state of the first two charge transitions. Independent gate control of the electron reservoirs also enables discrimination between excited states of the dot and density of states modulations in the leads.
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85.30.Tv Field effect devices
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Study of temporal current stability and fluctuations of field emitted electrons from ZnO nanostructure films

Kishore Uppireddi, Boqian Yang, Peter Xian Feng, and Gerardo Morell

Appl. Phys. Lett. 95, 242103 (2009); http://dx.doi.org/10.1063/1.3273383 (3 pages) | Cited 4 times

Online Publication Date: 14 December 2009

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Stable field emission currents and low fluctuations are important feasibility requirements for the application of materials in field emission devices and displays, more than the low turn on fields that are generally considered. The current stability and current fluctuations of field emitted electrons from ZnO nanostructures were investigated over the period of 2, 12, and 24 h. The films with nanoneedle structure having density around ten/μm2 showed better short and long-term (temporal) stability over a period of 24 h. The short- and long-term stability and the current fluctuations of the nanostructures are reported and the causes for the degradation of the emission current are discussed.
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79.70.+q Field emission, ionization, evaporation, and desorption
61.46.-w Structure of nanoscale materials
68.55.ag Semiconductors
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