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6 Aug 2007

Volume 91, Issue 6, Articles (06xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 91, 063118 (2007); http://dx.doi.org/10.1063/1.2768861 (3 pages)

Douglas C. Meier, Steve Semancik, Bradley Button, Evgheni Strelcov, and Andrei Kolmakov
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Blue-emitting AlN:Eu2+ nitride phosphor for field emission displays

N. Hirosaki, R.-J. Xie, K. Inoue, T. Sekiguchi, B. Dierre, and K. Tamura

Appl. Phys. Lett. 91, 061101 (2007); http://dx.doi.org/10.1063/1.2767182 (3 pages) | Cited 44 times

Online Publication Date: 6 August 2007

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An Eu2+-activated AlN phosphor was synthesized by firing the powder mixture of AlN, α-Si3N4, and Eu2O3 at 2050 °C for 4 h under 1.0 MPa N2. This nitride phosphor emits a strong blue color with the chromaticity coordinates of x = 0.139 and y = 0.106 at an accelerating voltage of 3 kV. The cathodoluminescence properties of AlN:Eu2+ was evaluated by utilizing it in the Spindt-type field emission display panel. It shows that the nitride phosphor exhibits higher brightness, higher color purity, lower saturation, and longer lifetime than the currently used Y2SiO5:Ce3+, indicative of the suitability of the AlN:Eu2+ blue phosphor in field emission displays.
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78.60.Hk Cathodoluminescence, ionoluminescence
85.45.Fd Field emission displays (FEDs)
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Planar amplifier for a microlaser on a cholesteric liquid crystal

L. M. Blinov, G. Cipparrone, V. V. Lazarev, and B. A. Umanskii

Appl. Phys. Lett. 91, 061102 (2007); http://dx.doi.org/10.1063/1.2762286 (3 pages) | Cited 4 times

Online Publication Date: 6 August 2007

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A planar device is described, which combines an oscillator (microlaser) based on a dye doped cholesteric liquid crystal and an amplifier made of another laser dye solution in glycerin. Both the oscillator and amplifier are pumped longitudinally with the same pump beam. With that simple 4 mm thick structure, the oscillator beam was amplified seven times.
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42.55.Mv Dye lasers
42.55.Sa Microcavity and microdisk lasers

Fabrication of organic light-emitting diode pixels by laser-assisted forward transfer

Romain Fardel, Matthias Nagel, Frank Nüesch, Thomas Lippert, and Alexander Wokaun

Appl. Phys. Lett. 91, 061103 (2007); http://dx.doi.org/10.1063/1.2759475 (3 pages) | Cited 35 times

Online Publication Date: 6 August 2007

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Fabrication of a polymer light-emitting device was achieved by a laser forward transfer technique using the decomposition of a thin triazene polymer film by a XeCl excimer laser. The dry deposition process allows transfer of a bilayer consisting of the electroluminescent polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] covered with an aluminum electrode onto a receiver substrate. The soft transfer results in laterally well resolved pixels ( ≈ 500 μm), whose fluorescence as well as electroluminescence spectra remain unaltered. The rectifying and smooth current-voltage characteristics add to the merits of this laser-based transfer method that opens up the possibility of direct-writing heat- and UV-sensitive materials.
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85.60.Bt Optoelectronic device characterization, design, and modeling
85.60.Jb Light-emitting devices
81.05.Bx Metals, semimetals, and alloys
81.15.Fg Pulsed laser ablation deposition

Composition dependence of structural and optical properties for sol-gel derived (100)-oriented Ba1−xSrxTiO3 thin films

G. S. Wang, Y. Y. Zhang, C. L. Mao, X. L. Dong, and J. H. Chu

Appl. Phys. Lett. 91, 061104 (2007); http://dx.doi.org/10.1063/1.2767986 (3 pages) | Cited 5 times

Online Publication Date: 6 August 2007

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Highly (100) oriented Ba1−xSrxTiO3 (BST) thin films were grown on LaNiO3 coated silicon substrate by modified sol-gel process. X-ray diffraction analysis shows that the out-of-plane lattice constant decreases linearly with increase of Sr concentration. The energy band gaps (Eg) of BST thin films exhibit strong dependence on Sr content by analyzing the results of the spectroscopic ellipsometer (SE) measurement. The smallest Eg has been obtained at x = 0.3, which is at the phase boundary of cube phase and tetragonal phase. The refractive index and thickness of BST thin films were obtained by fitting SE data with a multiphase model.
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68.55.-a Thin film structure and morphology
78.66.Nk Insulators
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
64.70.K- Solid-solid transitions

Simple lithographic approach for subwavelength structure antireflection

Sen Wang, Xiao Zheng Yu, and Hong Tao Fan

Appl. Phys. Lett. 91, 061105 (2007); http://dx.doi.org/10.1063/1.2767990 (3 pages) | Cited 35 times

Online Publication Date: 6 August 2007

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A simple lithographic method is developed to generate large-area antireflective subwavelength structures (SWSs), in which the metal island films are used as masks. Using magnetron sputter deposition, stochastically arranged Ag islands were fabricated on Si substrates with dimensions controlled in the range of 50 ∼ 400 nm. After reactive ion etching with CF4, Si SWSs were formed, with the same arrangement and density as those of Ag islands. The measured reflectivity was decreased from ∼ 40% for polished Si to ∼ 5% for Si SWS surfaces. The residual reflection was thought to be mainly from the bottoms of “U”-shape grooves.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Wc Optical coatings
68.55.A- Nucleation and growth
78.66.Bz Metals and metallic alloys
81.15.Cd Deposition by sputtering

Efficient spatial redistribution of quantum dot spontaneous emission from two-dimensional photonic crystals

M. Kaniber, A. Kress, A. Laucht, M. Bichler, R. Meyer, M.-C. Amann, and J. J. Finley

Appl. Phys. Lett. 91, 061106 (2007); http://dx.doi.org/10.1063/1.2757134 (3 pages) | Cited 18 times

Online Publication Date: 6 August 2007

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The authors investigate the modification of the spontaneous emission dynamics and the external quantum efficiency for self-assembled InGaAs quantum dots coupled to extended and localized photonic states in GaAs two-dimensional photonic crystals. The photonic band gap is shown to give rise to a five to ten times enhancement of the external quantum efficiency, while the spontaneous emission rate is simultaneously reduced by a comparable factor. The findings are quantitatively explained by a modal redistribution of spontaneous emission due to the modified local density of photonic states. The results suggest that quantum dots embedded within photonic crystals are suitable for practical single photon sources with high external efficiency.
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78.66.Fd III-V semiconductors
42.70.Qs Photonic bandgap materials

Optical conductance of waveguides built into finite photonic crystals

S. Albaladejo, J. J. Sáenz, M. Lester, L. S. Froufe-Pérez, and A. García-Martín

Appl. Phys. Lett. 91, 061107 (2007); http://dx.doi.org/10.1063/1.2761223 (3 pages) | Cited 7 times

Online Publication Date: 6 August 2007

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The concept of optical conductance is introduced in order to characterize the transport properties of waveguides built into finite photonic crystals. The conductance is given by the integral of the transmission cross section as a function of the incoming angle. This concept is illustrated by exact calculations of the light-guiding properties of a waveguide built into a photonic crystal slab based on a square lattice of dielectric cylinders in air. In analogy with their electronic counterparts, the optical conductance of a waveguide is quantized and thus provides a direct measure of the number of guided modes supported by the system.
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42.79.Gn Optical waveguides and couplers

Autoresonant control of the many-electron dynamics in nonparabolic quantum wells

G. Manfredi and P.-A. Hervieux

Appl. Phys. Lett. 91, 061108 (2007); http://dx.doi.org/10.1063/1.2761246 (3 pages) | Cited 31 times

Online Publication Date: 6 August 2007

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The optical response of nonparabolic quantum wells is dominated by a strong peak at the plasmon frequency. When the electrons reach the anharmonic regions, resonant absorption becomes inefficient. This limitation is overcome by using a chirped laser pulse in the autoresonant regime. By direct simulations using the Wigner phase-space approach, the authors prove that, with a sequence of just a few pulses, electrons can be efficiently detrapped from a nonparabolic well. For an array of multiple quantum wells, they can create and control an electronic current by suitably applying an autoresonant laser pulse and a slowly varying dc electric field.
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73.21.Fg Quantum wells
71.10.Ca Electron gas, Fermi gas

Increasing the operating temperature of boron doped silicon terahertz electroluminescence devices

G. Xuan, S. Kim, M. Coppinger, N. Sustersic, J. Kolodzey, and P.-C. Lv

Appl. Phys. Lett. 91, 061109 (2007); http://dx.doi.org/10.1063/1.2768195 (3 pages) | Cited 2 times

Online Publication Date: 6 August 2007

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High power electroluminescence near 8 THz was observed from boron doped silicon devices operating at heat sink temperatures up to 118 K. This represents the highest emission temperature yet observed for silicon dopant-based terahertz devices, and is a significant increase from previous reports. This letter compares the temperature dependence of the emission mechanism to the dopant occupation function and describes an empirical model that fits the variation of output power with temperature, and that can guide the design of future terahertz devices.
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85.60.Jb Light-emitting devices
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment

Reduction of etched AlGaAs sidewall roughness by oxygen-enhanced wet thermal oxidation

D. Liang and D. C. Hall

Appl. Phys. Lett. 91, 061110 (2007); http://dx.doi.org/10.1063/1.2766859 (3 pages) | Cited 5 times

Online Publication Date: 6 August 2007

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The authors demonstrate that the oxidation smoothing of sidewall roughness of dry-etched Al0.3Ga0.7As ridge structures is enabled through a modified wet thermal oxidation process which involves the addition of dilute amounts of O2 to the water vapor ambient. High magnification cross-section and top-view scanning electron microscope imagings both before and after oxide removal clearly show a substantial reduction of photolithography- and dry-etching-induced sidewall roughness (from σ ∼ 100 nm down to σ ∼ 1–2 nm), occurring only with the participation of added O2. The smoothing process provides means to realize high-index-contrast GaAs-based optical waveguides with both low bend and scattering losses.
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81.65.Cf Surface cleaning, etching, patterning
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)

Continuum generation and carving on a silicon chip

Prakash Koonath, Daniel R. Solli, and Bahram Jalali

Appl. Phys. Lett. 91, 061111 (2007); http://dx.doi.org/10.1063/1.2766962 (3 pages) | Cited 7 times

Online Publication Date: 6 August 2007

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Self-phase modulation is utilized to generate a continuum of wavelengths on a silicon chip. The propagation of near transform-limited, picosecond pulses (3 ps) through a micron sized silicon waveguide results in the generation of a spectral continuum. This spectral continuum is then carved by microdisk resonators that are integrated three dimensionally on the same chip, resulting in multiple wavelength channels, with the farthest channel being around 3.1 nm away from the center wavelength of the seed pulse. This technique can potentially enable wavelength division multiplexing at the chip level using a single off-chip laser.
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42.82.Ds Interconnects, including holographic interconnects
42.79.-e Optical elements, devices, and systems
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Nanoparticles-induced vertical alignment in liquid crystal cell

Shie-Chang Jeng, Chia-Wei Kuo, Hsing-Lung Wang, and Chi-Chang Liao

Appl. Phys. Lett. 91, 061112 (2007); http://dx.doi.org/10.1063/1.2768309 (3 pages) | Cited 33 times

Online Publication Date: 6 August 2007

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This letter reports that adding nanoparticles in the negative dielectric anisotropic liquid crystal (LC) cell can exhibit the properties of vertical alignment without using alignment layers. The electro-optical properties of this nanoparticles-induced vertical alignment in the LC cell are very similar to the conventional homeotropic LC cell with alignment layers. This technique can be used to fabricate a flexible LC display requiring a low temperature process.
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61.30.-v Liquid crystals
42.70.Df Liquid crystals
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals
78.20.Jq Electro-optical effects

Competition between two four-wave mixing channels via atomic coherence

Yanpeng Zhang, Blake Anderson, Andy W. Brown, and Min Xiao

Appl. Phys. Lett. 91, 061113 (2007); http://dx.doi.org/10.1063/1.2768872 (3 pages) | Cited 19 times

Online Publication Date: 8 August 2007

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Two four-wave-mixing (FWM) processes can coexist in a four-level Y-type atomic system with carefully arranged coupling laser beams. The generated two FWM signal beams fall into two simultaneously opened dual electromagnetically induced transparency (EIT) windows, which can be tuned to overlap or separate by various frequency detunings. The authors report our experimental observation of competing FWM processes, especially mutual suppression of the two FWM signals when the two EIT windows merge in frequency. Controlling FWM processes can have important applications in wavelength conversion for optical communication.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.60.Fc Modulation, tuning, and mode locking

Nanostructured solid-liquid compounds with rewritable optical functions

Mitsunori Saito, Yasuhiro Tsubokura, Narihito Ota, and Akiko Fujiuchi

Appl. Phys. Lett. 91, 061114 (2007); http://dx.doi.org/10.1063/1.2768908 (3 pages) | Cited 5 times

Online Publication Date: 8 August 2007

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Photosensitive solid-liquid compounds were fabricated by filling nanoholes of alumina or polymer films with dye solution. Although these compounds can be handled as solid in device fabrication processes, the liquid phase inside 50–200 nm holes provides a sufficient free volume for photochromic dye to change molecular structure. Nanoholes also prevent the solution to flow disturbing an optically written image. A function of the rewritable grating was demonstrated by bleaching a polycarbonate-based compound with various interference fringes of green laser.
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42.70.Gi Light-sensitive materials
42.70.Jk Polymers and organics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.79.Dj Gratings
42.65.-k Nonlinear optics

Scale-factor corrections in large ring lasers

B. Pritsch, K. U. Schreiber, A. Velikoseltsev, and J.-P. R. Wells

Appl. Phys. Lett. 91, 061115 (2007); http://dx.doi.org/10.1063/1.2768639 (3 pages) | Cited 3 times

Online Publication Date: 8 August 2007

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The authors report on fluctuations of the geometric scale factor of a very large ring laser situated 30 m underground in the Cashmere Cavern in Christchurch (New Zealand). Variations in temperature and atmospheric pressure cause thermoelastic deformations to the cavern, which lead to changes of the area and perimeter of the ring laser structure. In situ beam monitoring has been used to partially correct for these effects.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Thin-film silicon solar cells with efficient periodic light trapping texture

Christian Haase and Helmut Stiebig

Appl. Phys. Lett. 91, 061116 (2007); http://dx.doi.org/10.1063/1.2768882 (3 pages) | Cited 58 times

Online Publication Date: 8 August 2007

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For solar cells based on thin-film microcrystalline (μc-Si:H) or amorphous silicon (a-Si:H) with absorber layers in the micrometer range, highly effective light trapping and an optimal incoupling of the entire sun spectrum are essential. To investigate and optimize both effects the wave propagation in thin-film silicon solar cells is modeled in three dimensions (3D) solving the Maxwell equations rigorously. A periodic nanostructured texture is investigated as an alternative to the common randomly rough texture. Inverted 3D pyramids with a periodicity of 850 nm and structure height of 400 nm show promising high quantum efficiencies close to the Tiedje limit.
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84.60.Jt Photoelectric conversion
61.46.Hk Nanocrystals
61.72.-y Defects and impurities in crystals; microstructure

Role of optical gain broadening in the broadband semiconductor quantum-dot laser

C. L. Tan, Y. Wang, H. S. Djie, and B. S. Ooi

Appl. Phys. Lett. 91, 061117 (2007); http://dx.doi.org/10.1063/1.2762287 (3 pages) | Cited 9 times

Online Publication Date: 9 August 2007

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The authors present a theoretical model and analysis to gain a further insight of the broadband InGaAs/GaAs quantum-dot laser characteristics. A detailed analysis of the role of both inhomogeneous and homogeneous optical gain broadenings on the broad lasing emission is incorporated in the theoretical model and compared with the experimental results. The experimental data of broadband laser signature agrees well with theoretical calculation confirming that the broadband stimulated emission from the laser at room temperature is a result of the occurrence of bistate lasing in highly inhomogeneous dots.
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42.55.Px Semiconductor lasers; laser diodes

Acousto-optical multiple interference switches

M. Beck, M. M. de Lima, Jr., E. Wiebicke, W. Seidel, R. Hey, and P. V. Santos

Appl. Phys. Lett. 91, 061118 (2007); http://dx.doi.org/10.1063/1.2768889 (3 pages) | Cited 5 times

Online Publication Date: 9 August 2007

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The authors introduce an alternative approach for acousto-optical light control based on the interference of light propagating through several waveguides, each subjected to a periodic refractive index modulation induced by a surface acoustic wave. The feasibility of the concept is demonstrated by the realization of an optical switch for arbitrary time intervals with an on/off contrast ratio of 20.
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42.79.Jq Acousto-optical devices
43.38.Zp Acoustooptic and photoacoustic transducers

Enhanced luminescence of SrSi2O2N2:Eu2+ phosphors by codoping with Ce3+, Mn2+, and Dy3+ ions

Ru-Shi Liu, Yu-Huan Liu, Nitin C. Bagkar, and Shu-Fen Hu

Appl. Phys. Lett. 91, 061119 (2007); http://dx.doi.org/10.1063/1.2768916 (3 pages) | Cited 29 times

Online Publication Date: 9 August 2007

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The authors report here the enhanced luminescence properties of SrSi2O2N2 doped with Eu and M (M = Ce, Dy, and Mn). The Eu and Eu, Mn-codoped powders were prepared by a solid state reaction at temperatures between 1400 and 1600 °C under H2 (25%)–N2 (75%) atmosphere. The Eu, M-codoped Sr1−x−ySi2N2O2 phosphors have the monoclinic structure with lattice parameters a ∼ 15.6 Å, b ∼ 16.2 Å, c ∼ 9.4 Å, and β ∼ 91°. The phosphors can be efficiently excited in the UV to visible region, making them attractive as conversion phosphors for a light emitting diode application. A green-yellow emission was observed for Eu,M-codoped Sr1−x−ySi2N2O2. The addition of M in the Eu site in SrSi2O2N2 remarkably enhances the luminescent intensity by the factor of 144%, 148%, and 168% for Ce, Dy, and Mn, respectively.
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78.55.Hx Other solid inorganic materials

2.5λ microcavity InGaN light-emitting diodes fabricated by a selective dry-etch thinning process

Yong-Seok Choi, Michael Iza, Elison Matioli, Gregor Koblmüller, James S. Speck, Claude Weisbuch, and Evelyn L. Hu

Appl. Phys. Lett. 91, 061120 (2007); http://dx.doi.org/10.1063/1.2769397 (3 pages) | Cited 9 times

Online Publication Date: 9 August 2007

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The authors report on InGaN microcavity light-emitting diodes with an effective thickness of ∼ 450 nm at the emission wavelength of ∼ 415 nm. The starting material for the flip-chip laser lift-off device is a structure with an active region embedding six InGaN/GaN quantum wells, ∼ 60-nm-thick AlGaN, and a GaN template grown on a c-plane sapphire substrate. High-precision control of the final microcavity thickness was facilitated by SF6-based selective inductively coupled plasma etching on the flipped material with an etch rate of ≥ 5:1 for GaN:AlxGa1−xN, where x ≥ 0.15. Pronounced microcavity effects were observed by angular measurements, in agreement with the theoretical cavity-mode dispersion characteristics.
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85.60.Jb Light-emitting devices

Amplitude death in coupled chaotic solid-state lasers with cavity-configuration-dependent instabilities

Ming-Dar Wei and Jau-Ching Lun

Appl. Phys. Lett. 91, 061121 (2007); http://dx.doi.org/10.1063/1.2769757 (3 pages) | Cited 3 times

Online Publication Date: 9 August 2007

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In the mutually coupled Nd:YVO4 laser system with cavity-configuration-dependent instability, amplitude death was observed when the frequencies of the relaxation oscillation of the lasers were close to each other. Under asymmetrical coupling, the system followed a route via semiamplitude death to amplitude death. Simulation results support the existence of amplitude death in mutually coupled solid-state lasers with cavity-configuration-dependent instability.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics

Phase tunable multilevel diffractive optical element based single laser exposure fabrication of three-dimensional photonic crystal templates

Debashis Chanda and Peter R. Herman

Appl. Phys. Lett. 91, 061122 (2007); http://dx.doi.org/10.1063/1.2768867 (3 pages) | Cited 9 times

Online Publication Date: 10 August 2007

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The fabrication of diamond-like three-dimensional photonic crystal templates using a single laser exposure through a diffractive optical element has been demonstrated. An orthogonal combination of two linear phasemasks was used to define a two-dimensional diffractive optical element of multiple phase levels. By adjusting the gap between two phasemasks, a variable phase shift is shown by theory and demonstrated experimentally to control the interlacing position of two orthogonally rotated periodic structures. The transition of formation of diamond-like woodpile structures having tetragonal symmetry to structures having body-centered-tetragonal symmetry and variations in between has been demonstrated.
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42.70.Qs Photonic bandgap materials
42.62.-b Laser applications
42.86.+b Optical workshop techniques

Two-dimensional refractive index profiling by using differential near-field scanning optical microscopy

Wan-Shao Tsai, Way-Seen Wang, and Pei-Kuen Wei

Appl. Phys. Lett. 91, 061123 (2007); http://dx.doi.org/10.1063/1.2769396 (3 pages) | Cited 5 times

Online Publication Date: 10 August 2007

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The authors present two-dimensional reconstruction of the refractive index profile of an optical waveguide by using differential near-field optical microscopy. Using an inverse algorithm, the refractive index distribution is obtained directly from the measured optical near-field and its derivatives without any assumption of the index profile. The proposed method also takes advantage of subwavelength resolution and low noises in the waveguide region. Two-dimensional index profile reconstruction of a single mode fiber is measured for the demonstration. The measured optical field distribution and refractive index profile agree quite well with the calculated mode and the known index profile.
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07.60.Hv Refractometers and reflectometers
07.79.Fc Near-field scanning optical microscopes
07.60.Vg Fiber-optic instruments
42.81.Cn Fiber testing and measurement of fiber parameters

Plasmonic microzone plate: Superfocusing at visible regime

Yongqi Fu, W. Zhou, L. E. N. Lim, C. L. Du, and X. G. Luo

Appl. Phys. Lett. 91, 061124 (2007); http://dx.doi.org/10.1063/1.2769942 (3 pages) | Cited 53 times

Online Publication Date: 10 August 2007

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A silver film-based superlens, a plasmonic microzone plate, is put forth for the purpose of superfocusing at visible regime. The numerical analysis results reveal that it has unique focusing characteristics of longer focal length and depth of focus with resolving power beyond diffraction limit in comparison to the conventional zone plates. Working at near field, it increases working distance l at near field from l<λ/10 to l ≈ λ ∼ 5λ. This feature makes it a promising superlens to be used as a probe for the optical systems with high resolution imaging and detection as well as feedback control system immune for autofocusing.
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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)
42.30.-d Imaging and optical processing

Effects of the wave function localization in AlInGaN quaternary alloys

Fei Wang, Shu-Shen Li, Jian-Bai Xia, H. X. Jiang, J. Y. Lin, Jingbo Li, and Su-Huai Wei

Appl. Phys. Lett. 91, 061125 (2007); http://dx.doi.org/10.1063/1.2769958 (3 pages) | Cited 9 times

Online Publication Date: 10 August 2007

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Using the first-principles band-structure method and the special quasirandom structures approach, the authors have investigated the band structure of random AlxInyGa1−x−yN quaternary alloys. They show that the wave functions of the band edge states are more localized on the InN sites. Consequently, the photoluminescence transition intensity in the alloy is higher than that in GaN. The valence band maximum state of the quaternary alloy is also higher than GaN with the same band gap, indicating that the alloy can be doped more easily as p-type.
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71.20.Nr Semiconductor compounds
71.15.-m Methods of electronic structure calculations
78.55.Cr III-V semiconductors
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