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24 Apr 2006

Volume 88, Issue 17, Articles (17xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 88, 171109 (2006); http://dx.doi.org/10.1063/1.2197973 (3 pages)

J. A. Hagen, W. Li, A. J. Steckl, and J. G. Grote
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High-reflectivity ultraviolet AlGaN/AlGaN distributed Bragg reflectors

O. Mitrofanov, S. Schmult, M. J. Manfra, T. Siegrist, N. G. Weimann, A. M. Sergent, and R. J. Molnar

Appl. Phys. Lett. 88, 171101 (2006); http://dx.doi.org/10.1063/1.2195547 (3 pages) | Cited 9 times

Online Publication Date: 24 April 2006

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We demonstrate high-reflectivity crack-free Al0.18Ga0.82N/Al0.8Ga0.2N distributed Bragg reflectors (DBR) for the spectral region around 350 nm grown by molecular-beam epitaxy on thick GaN templates. The structural quality of the DBR layers is maintained by compensating the compressive and tensile stress in each λ/4 pair. This approach results in the lowest elastic strain energy and allows the growth of thick coherently strained DBRs. A 25 period mirror provides a 26 nm wide stop band centered at 347 nm with the maximum reflectivity higher than 99%.
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42.82.Bq Design and performance testing of integrated-optical systems
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Bh Lenses, prisms and mirrors
42.86.+b Optical workshop techniques

Large enhancement in second-harmonic generation by optical feedback

U. Chatterjee, S. Gangopadhyay, C. Ghosh, and G. C. Bhar

Appl. Phys. Lett. 88, 171102 (2006); http://dx.doi.org/10.1063/1.2198097 (3 pages) | Cited 1 time

Online Publication Date: 24 April 2006

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An optical feedback configuration is proposed for second-harmonic generation from a secondary coherent source in a nonlinear crystal that without focusing enables one to realize same conversion efficiency as obtained in a conventional setup but with at least four times less input fundamental energy. The effectiveness of the scheme is confirmed.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Effects of symmetry of GaN-based two-dimensional photonic crystal with quasicrystal lattices on enhancement of surface light extraction

Z. S. Zhang, B. Zhang, J. Xu, K. Xu, Z. J. Yang, Z. X. Qin, T. J. Yu, and D. P. Yu

Appl. Phys. Lett. 88, 171103 (2006); http://dx.doi.org/10.1063/1.2199491 (3 pages) | Cited 23 times

Online Publication Date: 24 April 2006

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We demonstrate enhancement of surface light extraction from two-dimensional photonic crystals (2D-PCs) on the electrical injected GaN-based light emitters. The effects of symmetry of PCs on light extraction were studied. 2.5 times enhancement of surface emission was obtained from the PCs with an octagonal symmetric quasicrystal lattice (8PQC) compared to that from a nonpatterned region. Additionally the surface emission from PCs with dodecagonal symmetric quasicrystal lattice (12PQC) exhibited about 1.7 and 1.4 times higher emission than regular PCs with triangular lattice and 8PQC, respectively. Consequently, the 12PQC provides a favorable consideration of 2D-PC in light extraction from light emitting diode.
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42.70.Qs Photonic bandgap materials
85.60.Jb Light-emitting devices

Integrated all-optical switch in a cross-waveguide geometry

N. Moll, R. Harbers, R. F. Mahrt, and G.-L. Bona

Appl. Phys. Lett. 88, 171104 (2006); http://dx.doi.org/10.1063/1.2197931 (3 pages) | Cited 15 times

Online Publication Date: 25 April 2006

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An all-optical switch for future computer optical interconnect systems based on an optical cavity with a high quality factor and a nonlinear material is computionally investigated in two dimensional with a finite-difference time domain method. The signal and control bus are perpendicular to each other and can couple into a high-Q cavity consisting of a nonlinear material. It is designed in such a way that the control bus switches the signal bus on and off. Owing to the nonlinearity in the cavity, the resonance is shifted in frequency when increasing the power in the control bus so that the signal can pass through the resonator. The high Q of the cavity maximizes the interaction with the nonlinear material, and the symmetry of the cavity mode is designed in such a way that the cross talk between the signal bus and the control bus is minimized.
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42.82.Gw Other integrated-optical elements and systems
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.82.Ds Interconnects, including holographic interconnects
42.82.Et Waveguides, couplers, and arrays
85.60.Bt Optoelectronic device characterization, design, and modeling
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Efficient vacuum ultraviolet light frequency downconversion by thin films of CdSe quantum dots

A. Kaplan, A. Sajwani, Z. Y. Li, R. E. Palmer, and J. P. Wilcoxon

Appl. Phys. Lett. 88, 171105 (2006); http://dx.doi.org/10.1063/1.2195697 (3 pages) | Cited 5 times

Online Publication Date: 25 April 2006

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Frequency downconversion is an effective method for the detection of ionizing radiation. We demonstrate the utilization of thin films of chemically synthesized CdSe quantum dots for this purpose. A high quantum yield of ∼ 0.2 is obtained at room temperature, which does not depend on the excitation wavelength in the range from 32 to 114 nm. The measured decay time is short, in the nanosecond regime, and the visible light output is stable. A significant advantage of such semiconductor quantum dots is the potential to tune the emission wavelength via selection of the nanoparticle size.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
78.67.Hc Quantum dots
78.47.-p Spectroscopy of solid state dynamics
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Fabrication of buried channel waveguides in photosensitive glass using proton beam writing

A. A. Bettiol, S. Venugopal Rao, E. J. Teo, J. A. van Kan, and Frank Watt

Appl. Phys. Lett. 88, 171106 (2006); http://dx.doi.org/10.1063/1.2198798 (3 pages) | Cited 21 times

Online Publication Date: 26 April 2006

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We report our results on the fabrication and characterization of buried, channel optical waveguides in photosensitive Foturan™ glass using a high energy proton beam. Waveguides were fabricated with varying fluence, and the propagation loss and refractive index change were measured. Near-field mode data measured at 632.8 nm showed that waveguiding could be achieved for all fluences ranging from 1014 to 1016 protons/cm2. The maximum positive refractive index change of 1.6×10−3 was measured for the highest fluence. The waveguide propagation losses measured using the scattering technique were estimated to be in the range of 8.3–12.9 dB/cm, increasing with proton fluence.
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42.79.Gn Optical waveguides and couplers
42.70.Ce Glasses, quartz
61.80.Jh Ion radiation effects
61.82.Ms Insulators

Development of three-dimensional photonic-crystal waveguides at optical-communication wavelengths

Masahiro Imada, Lye Hoe Lee, Makoto Okano, Shoichi Kawashima, and Susumu Noda

Appl. Phys. Lett. 88, 171107 (2006); http://dx.doi.org/10.1063/1.2197942 (3 pages) | Cited 22 times

Online Publication Date: 27 April 2006

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Photonic crystals have a photonic band gap (PBG) in which light propagation and emission is prohibited. In particular, three-dimensional (3D) photonic crystals have a complete PBG in all directions, which might allow the complete control of light emission and propagation in devices. Here, we report the first demonstration of light propagation in a 3D photonic-crystal waveguide at optical communication wavelengths. A line defect is introduced into a 3D photonic crystal composed of nine stacked layers, having a complete PBG in the 1.55 μm wavelength region. Light incident on the waveguide edge successfully propagates along the line-defect waveguide. The propagation characteristics agree with the calculated photonic band diagram of the structure. The calculated results indicate that lossless propagation becomes possible by increasing the number of layers in the device. These results are an important step toward the realization of multifunctional 3D photonic chips integrated within a small region.
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42.82.Et Waveguides, couplers, and arrays
42.70.Qs Photonic bandgap materials
42.79.Gn Optical waveguides and couplers

Tuning the focus of a plasmonic lens by the incident angle

Zhaowei Liu, Jennifer M. Steele, Hyesog Lee, and Xiang Zhang

Appl. Phys. Lett. 88, 171108 (2006); http://dx.doi.org/10.1063/1.2188378 (3 pages) | Cited 56 times

Online Publication Date: 27 April 2006

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We report the experimental realization of tuning the focus position of a plasmonic lens by adjusting the angle of the incident light similar to conventional lenses. A circular slit in silver film acts as both a surface plasmon polariton coupler and a plasmonic focusing lens. At small incident angles, the plasmonic lens has a very good focus with the position depending only on the angle of the incident beam. Numerical simulations of the focusing properties, including polarization dependence, agree well with experimental observations. This tunable plasmonic lens can be used in nanoscale photonics, biological sensing, and manipulation.
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42.79.Bh Lenses, prisms and mirrors
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)

Enhanced emission efficiency in organic light-emitting diodes using deoxyribonucleic acid complex as an electron blocking layer

J. A. Hagen, W. Li, A. J. Steckl, and J. G. Grote

Appl. Phys. Lett. 88, 171109 (2006); http://dx.doi.org/10.1063/1.2197973 (3 pages) | Cited 77 times

Online Publication Date: 28 April 2006

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Enhanced electroluminescent efficiency using a deoxyribonucleic acid (DNA) complex as an electron blocking (EB) material has been demonstrated in both green- and blue-emitting organic light-emitting diodes (OLEDs). The resulting so-called BioLEDs showed a maximum luminous efficiency of 8.2 and 0.8 cd/A, respectively. The DNA-based BioLEDs were as much as 10× more efficient and 30× brighter than their OLED counterparts.
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85.60.Jb Light-emitting devices
87.14.G- Nucleic acids

Very low threshold, carrier-confined diode lasers by a single selective area growth

Jianxin Cai, Fow-Sen Choa, Yonglin Gu, Xiaoming Ji, Jingzhou Yan, Guoyun Ru, Liwei Cheng, and Jenyu Fan

Appl. Phys. Lett. 88, 171110 (2006); http://dx.doi.org/10.1063/1.2200471 (3 pages) | Cited 1 time

Online Publication Date: 28 April 2006

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Very low threshold, carrier-confined semiconductor lasers made of a single selective area growth by metal organic chemical vapor deposition without using any regrowth are reported. Room-temperature continuous wave threshold of 2.7 mA emitting around 1.54 μm was achieved from as-cleaved facet. The fabricated lasers have good uniformity across the wafer and initial aging test shows that the laser is reliable.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Fabrication of freestanding semiconductor multiquantum-well microtubes

A. Majumdar, Z. P. Guan, F. Zhao, D. Li, D. Ray, S. Jain, S. Mukherjee, and Z. Shi

Appl. Phys. Lett. 88, 171111 (2006); http://dx.doi.org/10.1063/1.2195900 (3 pages) | Cited 2 times

Online Publication Date: 28 April 2006

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We report a freestanding micrometer-size tube structure of molecular beam epitaxy grown lead-salt multiple quantum well (MQW). The MQW microtube maintains a high monocrystalline quality as evidenced by a strong photoluminescence emission from the tube structure. A theoretical model based on residual stress is used to explain the tube formation and matches the experimental results well.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.Fg Quantum wells

Multibeam interferometric illumination as the primary source of resolution in optical microscopy

J. Ryu, S. S. Hong, B. K. P. Horn, D. M. Freeman, and M. S. Mermelstein

Appl. Phys. Lett. 88, 171112 (2006); http://dx.doi.org/10.1063/1.2192153 (3 pages) | Cited 10 times

Online Publication Date: 28 April 2006

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High-resolution images of a fluorescent target were obtained using a low-resolution optical detector by illuminating the target with interference patterns produced with 31 coherent beams. The beams were arranged in a cone with 78° half angle to produce illumination patterns consistent with a numerical aperture of 0.98. High-resolution images were constructed from low-resolution images taken with 930 different illumination patterns. Results for optical detectors with numerical apertures of 0.1 and 0.2 were similar, demonstrating that the resolution is primarily determined by the illuminator and not by the low-resolution detector. Furthermore, the long working distance, large depth of field, and large field of view of the low-resolution detector are preserved.
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07.60.Pb Conventional optical microscopes
07.60.Ly Interferometers
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR
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Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets

J. L. Walsh, J. J. Shi, and M. G. Kong

Appl. Phys. Lett. 88, 171501 (2006); http://dx.doi.org/10.1063/1.2198100 (3 pages) | Cited 89 times

Online Publication Date: 26 April 2006

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Pulsed excitation of cold atmospheric plasmas is commonly believed to offer valuable benefits compared to the mainstream sinusoidal excitation. However, direct comparison of pulsed and sinusoidal atmospheric plasmas remains few, if any, thus casting an uncertainty of whether pulsed excitation facilitates any significant advantage. In this letter, we report a comparison study of pulsed and sinusoidal cold atmospheric plasma jets through electrical characterization, gas temperature measurement, and optical detection of reactive plasma species. An example of pulsed excitation is shown to reduce the electrical energy consumption by a factor of 12 for producing the same amount of oxygen atoms.
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52.50.Dg Plasma sources
52.80.Hc Glow; corona
52.70.Ds Electric and magnetic measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Time-resolved pump probe of 1.55 μm InAs/InP quantum dots under high resonant excitation

C. Cornet, C. Labbé, H. Folliot, P. Caroff, C. Levallois, O. Dehaese, J. Even, A. Le Corre, and S. Loualiche

Appl. Phys. Lett. 88, 171502 (2006); http://dx.doi.org/10.1063/1.2199454 (3 pages) | Cited 14 times

Online Publication Date: 26 April 2006

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We have performed time-resolved resonant pump-probe experiment to study the dynamic response of InAs/InP quantum dot transitions. A 72-stacked InAs/InP quantum dot layer sample is grown on (311)B substrate. Photoluminescence at high excitation power reveals ground and excited transitions. Carrier radiative lifetimes and differential transmission are determined under strong excitation powers. The variation of measured carrier radiative lifetimes with increasing excitation powers is attributed to the exciton and biexciton lifetimes difference. The implications of such a difference on differential transmission are discussed, and finally exciton and biexciton lifetimes are measured to be about 1720 and 530 ps, respectively.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.35.-y Excitons and related phenomena

Spectroscopic study of debris mitigation with minimum-mass Sn laser plasma for extreme ultraviolet lithography

S. Namba, S. Fujioka, H. Nishimura, Y. Yasuda, K. Nagai, N. Miyanaga, Y. Izawa, K. Mima, and K. Takiyama

Appl. Phys. Lett. 88, 171503 (2006); http://dx.doi.org/10.1063/1.2199494 (3 pages) | Cited 19 times

Online Publication Date: 27 April 2006

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An experimental study was made of a target consisting of the minimum mass of pure tin (Sn) necessary for the highest conversion to extreme ultraviolet (EUV) light while minimizing the generation of plasma debris. The minimum-mass target comprised a thin Sn layer coated on a plastic shell and was irradiated with a Nd:YAG laser pulse. The expansion behavior of neutral atoms and singly charged ions emanating from the Sn plasma were investigated by spatially resolved visible spectroscopy. A remarkable reduction of debris emission in the backward direction with respect to the incident laser beam was demonstrated with a decrease in the thickness of the Sn layer. The optimal thickness of the Sn layer for a laser pulse of 9 ns at 7×1010 W/cm2 was found to be 40 nm, at which low-debris emission in the backward direction and a high conversion to 13.5 nm EUV radiation were simultaneously attained.
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78.40.Kc Metals, semimetals, and alloys
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
81.16.Nd Micro- and nanolithography
78.47.-p Spectroscopy of solid state dynamics
42.62.-b Laser applications
52.77.-j Plasma applications
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Determination of deformation potentials in strained InSb quantum wells

T. Kasturiarachchi, F. Brown, N. Dai, G. A. Khodaparast, R. E. Doezema, S. J. Chung, and M. B. Santos

Appl. Phys. Lett. 88, 171901 (2006); http://dx.doi.org/10.1063/1.2198101 (3 pages) | Cited 2 times

Online Publication Date: 25 April 2006

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We use interband exciton transitions in InSb/AlxIn1−xSb multi-quantum-well samples to determine the heavy-hole and light-hole energy gaps as the strain is varied using Al concentrations up to 25%. The gaps are compared to deformation-dependent calculations of the energy gaps in the presence of biaxial strain to obtain a measure of the deformation potentials α and β.
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73.21.Fg Quantum wells
71.35.-y Excitons and related phenomena

Evidence of temperature dependence of initial adsorption sites of Ge atoms on Si(111)-7×7

Zubaida A. Ansari, Masahiko Tomitori, and Toyoko Arai

Appl. Phys. Lett. 88, 171902 (2006); http://dx.doi.org/10.1063/1.2198109 (3 pages) | Cited 7 times

Online Publication Date: 25 April 2006

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Small amounts of Ge atoms are deposited on Si(111)-7×7 surfaces at room temperature (RT) and at 100 °C to clarify the initial adsorption sites using scanning tunneling microscopy. At RT Ge atoms are adsorbed at high coordination B2 sites around the rest atoms, as predicted by Cho and Kaxiras [Surf. Sci. 396, L261 (1998) ]. On one hand, at 100 °C Ge atoms are adsorbed on corner adatom sites. With increasing Ge coverage the corner sites are gradually occupied, followed by Ge adsorption at center adatom sites, resulting in Ge cluster growth with a size of the half unit cell.
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68.43.Mn Adsorption kinetics
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Governing equation for the measurement of nonuniform stress distributions in thin films using a substrate deformation technique

Meiling Zhu and Paul B. Kirby

Appl. Phys. Lett. 88, 171903 (2006); http://dx.doi.org/10.1063/1.2189448 (3 pages) | Cited 2 times

Online Publication Date: 25 April 2006

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Determination of stress in thin films deposited on substrates is a basic and essential requirement in micronanotechnology. Most often local measurements of the induced substrate curvature are related to local stress using the Stoney equation. However, it is well known that this method gives incorrect results if the stress distribution is nonuniform. Here a general governing equation for the evaluation of nonuniform stress distributions in thin films is derived, which has the new feature of being able to treat the cases of anisotropic stress and also the effect on substrate deformation of a large in-plane thin film tension.
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68.60.Bs Mechanical and acoustical properties
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity

Prediction of the bulk elastic constant of metals using atomic-level single-lattice analytical method

Kuo-Ning Chiang, Chan-Yen Chou, Chung-Jung Wu, and Chang-Ann Yuan

Appl. Phys. Lett. 88, 171904 (2006); http://dx.doi.org/10.1063/1.2198112 (3 pages) | Cited 4 times

Online Publication Date: 25 April 2006

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An atomic-level single-lattice method with a closed-form equation is presented to predict the elastic characteristics of bulk metals. In this letter, the interatomic forces of single body-centered-cubic (bcc) and face-centered-cubic (fcc) lattices are described as atomic springs, the single bcc and fcc lattices are therefore constructed as simple spring network models. The analytical result indicates that the calculated single-lattice elastic characteristics and the experimental bulk values are within a reasonable range. This analytical equation also provides a feasible way of taking a second look at the Morse potential coefficients of metallic atoms.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
34.20.Cf Interatomic potentials and forces

Thermodynamic modeling of glass formation in metallic glasses

L. Xia, S. S. Fang, Q. Wang, Y. D. Dong, and C. T. Liu

Appl. Phys. Lett. 88, 171905 (2006); http://dx.doi.org/10.1063/1.2198830 (3 pages) | Cited 24 times

Online Publication Date: 25 April 2006

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In the study of metallic glasses, it is vitally important for us to understand glass formation and glass forming ability (GFA). This letter presents a thermodynamic model for evaluating glass formation in metallic glasses. An expression has been derived from considering both the stability of amorphous phases and the resistance to the formation of crystalline intermetallic phases. This equation is very useful for identifying alloy compositions with good GFA in binary and other alloy systems. The prediction of this equation has been verified by the experimental study of glass formation and glass forming ability in the Zr–Cu system.
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65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
61.43.Fs Glasses

Pressure tunes atomic packing in metallic glass

H. W. Sheng, E. Ma, H. Z. Liu, and J. Wen

Appl. Phys. Lett. 88, 171906 (2006); http://dx.doi.org/10.1063/1.2197315 (3 pages) | Cited 9 times

Online Publication Date: 25 April 2006

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By employing the state-of-the-art in situ high-pressure synchrotron x-ray measurements and ab initio modeling, we have resolved atomic-level packing details in a metallic glass as a function of pressure. We demonstrate pronounced changes in atomic size ratio (and correspondingly coordination number) with increasing pressure and the accompanying conversion of prism-type coordination to icosahedral short-range order.
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61.43.Fs Glasses
62.50.-p High-pressure effects in solids and liquids
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
64.70.K- Solid-solid transitions

Wide-band “black silicon” based on porous silicon

L. L. Ma, Y. C. Zhou, N. Jiang, X. Lu, J. Shao, W. Lu, J. Ge, X. M. Ding, and X. Y. Hou

Appl. Phys. Lett. 88, 171907 (2006); http://dx.doi.org/10.1063/1.2199593 (3 pages) | Cited 39 times

Online Publication Date: 25 April 2006

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Solar cells and optical detection devices often incorporate antireflective surfaces to reduce undesired reflection and enhance optical absorption. This letter reports a “black silicon” structure of antireflective porous silicon fabricated by using electrochemical etching. The sample has a gradient-index multilayer structure, i.e., the refraction indices of the structure increase from the top (near the air) to the bottom (near the Si substrate). Reflectance below 5% is obtained over a broad wave number range (3000–28000 cm−1) and the depression mechanism of the optical reflectance is analyzed by simulating the structure with the transfer matrix method. The simulated result fits the measured spectra well.
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61.43.Gt Powders, porous materials
68.65.Ac Multilayers
81.65.Cf Surface cleaning, etching, patterning
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials

Atomic force probe for sidewall scanning of nano- and microstructures

Gaoliang Dai, Helmut Wolff, Frank Pohlenz, Hans-Ulrich Danzebrink, and Günter Wilkening

Appl. Phys. Lett. 88, 171908 (2006); http://dx.doi.org/10.1063/1.2198516 (3 pages) | Cited 15 times

Online Publication Date: 26 April 2006

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An atomic force microscope (AFM) probe applicable for sidewall scanning has been developed. In its configuration, a horizontal AFM cantilever is microassembled with a vertical AFM cantilever. An AFM tip located at the free end of the vertical cantilever and extending horizontally is capable of probing in a direction perpendicular to sidewalls. The bending, torsion, or deformation of the horizontal cantilever is detected when the tip is brought into contact, intermittent contact, or noncontact with sidewalls. Measurement results taken at the sidewalls of microtrenches, microgears, and line edge roughness samples are presented.
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07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
62.25.-g Mechanical properties of nanoscale systems
68.35.B- Structure of clean surfaces (and surface reconstruction)

Growth of III-nitride photonic structures on large area silicon substrates

J. Li, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 88, 171909 (2006); http://dx.doi.org/10.1063/1.2199492 (3 pages) | Cited 15 times

Online Publication Date: 26 April 2006

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We report on the growth of high quality aluminum nitride (AlN) and gallium nitride (GaN) epilayers on large area (6 in. diameter) silicon (111) substrates by metal organic chemical vapor deposition. We have demonstrated the feasibility of growing crack-free high quality III-nitride photonic structures and devices on 6 inch Si substrates through the fabrication of blue light emitting diodes based upon nitride multiple quantum wells with high performance. The demonstration further enhances the prospects for achieving photonic integrated circuits based upon nitride-on-Si material system.
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68.65.Fg Quantum wells
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Violet photoluminescence from shell layer of Zn/ZnO core-shell nanoparticles induced by laser ablation

Haibo Zeng, Weiping Cai, Jinlian Hu, Guotao Duan, Peisheng Liu, and Yue Li

Appl. Phys. Lett. 88, 171910 (2006); http://dx.doi.org/10.1063/1.2196051 (3 pages) | Cited 64 times

Online Publication Date: 27 April 2006

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A strong violet photoluminescence (PL) band at 425 nm (2.92 eV) was observed from the ZnO shell layer of the Zn/ZnO core-shell nanoparticles prepared by laser ablation in liquid media. Such violet PL decreases with increase of the shell thickness or annealing temperature, showing good controllability. Based on the electron paramagnetic resonance measurements, the violet emission is attributed to the electronic transition from the defect level, corresponding to high-concentration zinc interstitials, to the valence band. This study is in favor to clarify the defect-related emissions and to extend the optical and electronic applications of nanostructured ZnO.
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78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
73.22.-f Electronic structure of nanoscale materials and related systems
71.20.Nr Semiconductor compounds
52.38.Mf Laser ablation
61.82.Fk Semiconductors
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