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13 May 2002

Volume 80, Issue 19, pp. 3467-3650

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Gain trimming of the resonant characteristics in vertically coupled InP microdisk switches

Kostadin Djordjev, Seung-June Choi, Sang-Jun Choi, and P. D. Dapkus

Appl. Phys. Lett. 80, 3467 (2002); http://dx.doi.org/10.1063/1.1476701 (3 pages) | Cited 14 times

Online Publication Date: 7 May 2002

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InP, vertically coupled microdisk resonator/waveguide switches with a gain active region are demonstrated. The devices exhibit single-mode operation, large free-spectral range of 10 nm, and a high-quality factor of 5700. The introduction of a quantum-well region inside the cavity provides a way of gain trimming the resonant characteristics. Active switches, routers, and filters with tunable bandwidth based on these devices are envisioned as part of a wavelength division multiplexing system. © 2002 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.82.Bq Design and performance testing of integrated-optical systems
42.79.Gn Optical waveguides and couplers

Organic light-emitting devices for illumination quality white light

Anil R. Duggal, J. J. Shiang, Christian M. Heller, and Donald F. Foust

Appl. Phys. Lett. 80, 3470 (2002); http://dx.doi.org/10.1063/1.1478786 (3 pages) | Cited 114 times

Online Publication Date: 7 May 2002

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A method of generating white light by combining a blue organic light-emitting diode with a down-conversion phosphor system is presented. It is demonstrated that the use of the down-conversion phosphor system actually leads to an overall power efficiency increase, an effect attributed to the high quantum efficiency of phosphor materials and the presence of light scattering in the phosphor layers. It is also shown that this approach permits the generation of illumination quality white light over the full range of color temperatures required for lighting applications. For the model device demonstrated in this work, an overall electrical to optical power conversion efficiency of 1.3% was achieved at a brightness of 1080 cd/m2. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters
42.72.Bj Visible and ultraviolet sources

Optical waveguides formed in Nd:YVO4 by MeV Si+ implantation

Feng Chen, Xue-Lin Wang, Ke-Ming Wang, Qing-Ming Lu, and Ding-Yu Shen

Appl. Phys. Lett. 80, 3473 (2002); http://dx.doi.org/10.1063/1.1477939 (3 pages) | Cited 24 times

Online Publication Date: 7 May 2002

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The planar waveguide has been fabricated in a Nd:YVO4 crystal by 3.0 MeV Si+ ion implantation at a dose of 1×1015 ions/cm2 at room temperature. The waveguide was characterized by the prism-coupling method. The dark modes are measured before and after the annealing at 240 °C for 60 min in air. The refractive index profile is reconstructed using reflectivity calculation method. It is found that relatively large positive change of ordinary refractive index happens in the guiding region, which is quite different from most of the observed ion-implanted waveguides. The TRIM’98 code is carried out to simulate the energy loss during the implantation in order to obtain a better understanding for the waveguide formation. © 2002 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers

Very-low-threshold photonic band-edge lasers from free-standing triangular photonic crystal slabs

Han-Youl Ryu, Soon-Hong Kwon, Yong-Jae Lee, Yong-Hee Lee, and Jeong-Soo Kim

Appl. Phys. Lett. 80, 3476 (2002); http://dx.doi.org/10.1063/1.1477617 (3 pages) | Cited 61 times

Online Publication Date: 7 May 2002

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Photonic band-edge lasers are realized in the free-standing triangular photonic crystal slab with InGaAsP quantum wells at 80 K. Surface-emitting lasing actions are observed from the samples whose wavelengths correspond to the second or the third photonic band edge near the Γ point of the band structure, which is confirmed by the three-dimensional finite-different time-domain calculation. A very low threshold of 35 μW (incident pump power) is achieved from the laser operating near the third transverse-electric-mode band edge. This low threshold is benefited from low optical losses near the Γ point as well as reduced surface recombination carrier losses and enhanced material gain at low temperature. It is interesting to note that this two-dimensional distributed feedback lasing action is observed from a surprisingly small pump area of 6 μm in diameter. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.70.Qs Photonic bandgap materials
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Near-field second-harmonic generation at a metal tip apex

Satoshi Takahashi and Anatoly V. Zayats

Appl. Phys. Lett. 80, 3479 (2002); http://dx.doi.org/10.1063/1.1478780 (3 pages) | Cited 12 times

Online Publication Date: 7 May 2002

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Second-harmonic generation at a gold tip apex has been studied within the context of applications in apertureless scanning near-field microscopy. Polarization and distance dependencies of second-harmonic generation have been investigated and compared to respective dependencies for scattered fundamental light. The results shows that, in general, different topological features of a tip are responsible for scattering and second-harmonic generation in the far and near field. The near-field interaction between a probe tip and a surface significantly modifies enhancement of the electromagnetic field at the tip and results in different distance dependencies of near-field scattering and second-harmonic generation. The polarization contrast obtained with the second-harmonic signal significantly exceeds the polarization contrast of linear scattering from the tip. © 2002 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
81.05.Bx Metals, semimetals, and alloys
07.79.Fc Near-field scanning optical microscopes
68.37.Uv Near-field scanning microscopy and spectroscopy

Tunnel injection In0.4Ga0.6As/GaAs quantum dot lasers with 15 GHz modulation bandwidth at room temperature

P. Bhattacharya and S. Ghosh

Appl. Phys. Lett. 80, 3482 (2002); http://dx.doi.org/10.1063/1.1478129 (3 pages) | Cited 54 times

Online Publication Date: 7 May 2002

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By utilizing tunnel injection of electrons, first demonstrated in quantum well lasers, we have measured enhanced small-signal modulation bandwidth, f−3dB, and reduced temperature sensitivity of the threshold current, characterized by T0, in In0.4Ga0.6As/GaAs self-organized quantum dot ridge waveguide lasers. Values of f−3dB = 15 GHz at 283 K and T0 = 237 K for 318 ≥ T ≥ 278 are measured in these devices. The differential gain at 283 K is dg/dn ≅ 8.5×10−14 cm2 and the gain compression factor ϵ = 4.5×10−17 cm3. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.67.Hc Quantum dots
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.07.Ta Quantum dots
85.30.De Semiconductor-device characterization, design, and modeling

Praseodymium oxide coated anode for organic light-emitting diode

Chengfeng Qiu, Haiying Chen, Zhiliang Xie, Man Wong, and Hoi Sing Kwok

Appl. Phys. Lett. 80, 3485 (2002); http://dx.doi.org/10.1063/1.1476712 (3 pages) | Cited 22 times

Online Publication Date: 7 May 2002

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Capping an indium–tin–oxide anode with a thin layer of praseodymium oxide (Pr2O3) has been found to enhance not only hole-injection, quantum, and power efficiencies but also the lifetime of organic light-emitting diode made using copper (II) phthalocyanine as the anode buffer layer, N, N′-diphenyl-N,N′ bis(3-methylphenyl-1,1′-biphenyl-4,4′-diamine as the hole-transport layer and tris-8-hydroxyquinoline aluminum as the electron-transport/emission layer. The best results have been obtained on diodes with ∼ 1 nm thick Pr2O3. A possible mechanism behind the improvement is discussed. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
73.30.+y Surface double layers, Schottky barriers, and work functions
73.61.Ph Polymers; organic compounds
78.66.Qn Polymers; organic compounds
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Measurement of transverse electric and transverse magnetic spontaneous emission and gain in tensile strained GaInP laser diodes

G. M. Lewis, P. M. Smowton, P. Blood, G. Jones, and S. Bland

Appl. Phys. Lett. 80, 3488 (2002); http://dx.doi.org/10.1063/1.1476396 (3 pages) | Cited 8 times

Online Publication Date: 7 May 2002

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We have measured the modal gain and spontaneous emission spectra of a 0.8% tensile-strained GaInP laser structure in transverse electric (TE) and transverse magnetic (TM) polarizations by analysis of the single-pass amplified spontaneous emission from the end of a segmented-contact structure. The absolute values of the true spontaneous emission rates have been determined for both polarizations. Data for the TEy and TM peak gain as functions of the total intrinsic radiative current can be fitted with the usual logarithmic relation with a transparency current density of 99 A cm−2 and with the (electron–light-hole) TM/TEy gains in the ratio 4:1 as predicted from the oscillator strengths. Spontaneous emission into the TM modes accounts for 48% of the total radiative current. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors

Evidence for braggoriton excitations in opal photonic crystals infiltrated with highly polarizable dyes

N. Eradat, A. Y. Sivachenko, M. E. Raikh, Z. V. Vardeny, A. A. Zakhidov, and R. H. Baughman

Appl. Phys. Lett. 80, 3491 (2002); http://dx.doi.org/10.1063/1.1479197 (3 pages) | Cited 16 times

Online Publication Date: 7 May 2002

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We studied angle-dependent reflectivity spectra of opal photonic crystals infiltrated with cyanine dye aggregates, which are highly polarizable media with very large Rabi frequency. We show that, at resonance condition between the exciton-polariton of the dye aggregate and the Bragg gap, the Bragg stop band decomposes into two reflectivity bands with a semitransparent spectral range in between, that is due to propagation of braggoritons inside the gap. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
71.35.Gg Exciton-mediated interactions
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
63.20.kk Phonon interactions with other quasiparticles

Enhancement of the coupling efficiency in optical fibers using a two-beam optical interference

M. Kamel Amara and Noureddine Melikechi

Appl. Phys. Lett. 80, 3494 (2002); http://dx.doi.org/10.1063/1.1479195 (3 pages) | Cited 1 time

Online Publication Date: 7 May 2002

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We report on an experimental technique, based on the launch of the central fringe of a two-beam interference pattern into an optical fiber that allows considerable enhancement of the coupling efficiency. Using helium–neon laser operating at 633 nm and a 3.3 μm wide fiber with a numerical aperture of 0.16, we have obtained a coupling efficiency of about 91%. © 2002 American Institute of Physics.
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42.81.Dp Propagation, scattering, and losses; solitons
42.81.Qb Fiber waveguides, couplers, and arrays
42.25.Hz Interference

High-power 400-nm-band AlGaInN-based laser diodes with low aspect ratio

T. Asano, M. Takeya, T. Tojyo, T. Mizuno, S. Ikeda, K. Shibuya, T. Hino, S. Uchida, and M. Ikeda

Appl. Phys. Lett. 80, 3497 (2002); http://dx.doi.org/10.1063/1.1478157 (3 pages) | Cited 21 times

Online Publication Date: 7 May 2002

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High-power blue-violet laser diodes with aspect ratio as low as 2.3 and threshold current down to 33 mA have been realized. The relationship between threshold current and optical confinement factor was investigated in order to minimize the beam divergence angle perpendicular to the junction plane (θ⊥). θ⊥ was found to decrease with reduction of the optical confinement factor, whereas threshold current density increased. A new layer structure, in which a p-typed cladding layer was located next to an AlGaN electron blocking layer, and a GaInN guiding layer was inserted between the active and the AlGaN electron blocking layer, was effective for obtaining small θ⊥ while maintaining low threshold current. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.30.De Semiconductor-device characterization, design, and modeling
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Fabrication of frequency-selective surfaces using microlens projection photolithography

Ming-Hsien Wu, Kateri E. Paul, Jerry Yang, and George M. Whitesides

Appl. Phys. Lett. 80, 3500 (2002); http://dx.doi.org/10.1063/1.1477941 (3 pages) | Cited 10 times

Online Publication Date: 7 May 2002

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This letter describes the use of microlens projection photolithography (μLPL) for the fabrication of repetitive metallic micropatterns, and the application of these patterns as frequency-selective surfaces. Microlens projection photolithography uses an array of microlenses (diameter d = 1–1000 micrometers) to project an array of images of an illuminated mask into photoresist. We converted these arrays into patterns in metals by electron beam evaporation and lift off. This technique can produce arrays over areas >10 cm2 with submicrometer feature sizes in a single exposure. We fabricated arrays of metallic micropatterns on substrates transparent to infrared radiation, and demonstrated that appropriate patterns acted as frequency-selective filters. © 2002 American Institute of Physics.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Bh Lenses, prisms and mirrors

Polarization switching in optical microsphere resonator

A. Yu. Smirnov, S. N. Rashkeev, and A. M. Zagoskin

Appl. Phys. Lett. 80, 3503 (2002); http://dx.doi.org/10.1063/1.1477277 (3 pages) | Cited 8 times

Online Publication Date: 7 May 2002

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A general electrodynamical theory of a high-Q optical microsphere resonator in an external alternating magnetic field is reported. We show that such a system can change a polarization state of the whispering-gallery-mode photons confined in the sphere due to the Faraday effect. This property can be used in all-optical switches and logical devices. The contribution of the Kerr nonlinearities is also discussed. © 2002 American Institute of Physics.
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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
78.20.Ls Magneto-optical effects
77.22.Ej Polarization and depolarization
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Design of short-cavity, high-brightness 980 nm laser diodes with distributed phase correction

Y. Zhang, J. J. Lim, T. M. Benson, P. Sewell, S. Dods, and E. C. Larkins

Appl. Phys. Lett. 80, 3506 (2002); http://dx.doi.org/10.1063/1.1474618 (3 pages)

Online Publication Date: 7 May 2002

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We present the design of a 980 nm short-cavity, high-brightness, laterally graded-index (GRIN) laser diode with distributed phase correction. The proposed laser consists of a feed waveguide section coupled to a GRIN waveguide region with a discretized hyperbolic-secant index profile. Detailed wide-angle two-dimensional finite-difference beam propagation method simulations show that this lateral GRIN laser will exhibit significant performance improvements over comparable tapered lasers. © 2002 American Institute of Physics.
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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
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Molecular-beam epitaxy growth of high-quality active regions with strained InxGa1−xAs quantum wells and lattice-matched AlxGayIn(1−x−y)As barriers using submonolayer superlattices

M. H. M. Reddy, A. Huntington, D. Buell, R. Koda, E. Hall, and L. A. Coldren

Appl. Phys. Lett. 80, 3509 (2002); http://dx.doi.org/10.1063/1.1474598 (3 pages) | Cited 7 times

Online Publication Date: 7 May 2002

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Submonolayer superlattices (SMS) of Ga0.47In0.53As/InAs/Ga0.47In0.52As and Ga0.47In0.53As/Al0.48In0.52As were used for the growth of strained quantum wells (QWs) and lattice-matched barriers, respectively, in the 1.55 μm active region. QWs grown with different compressive strains show excellent room-temperature photoluminescence, demonstrating the versatility of this technique. State-of-the-art current thresholds are reported for the broad-area lasers fabricated using the SMS active region. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
68.65.Cd Superlattices
68.65.Fg Quantum wells
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.35.Ct Interface structure and roughness
81.07.St Quantum wells

Stimulated terahertz emission from group-V donors in silicon under intracenter photoexcitation

V. N. Shastin, R. Kh. Zhukavin, E. E. Orlova, S. G. Pavlov, M. H. Rümmeli, H.-W. Hübers, J. N. Hovenier, T. O. Klaassen, H. Riemann, I. V. Bradley, and A. F. G. van der Meer

Appl. Phys. Lett. 80, 3512 (2002); http://dx.doi.org/10.1063/1.1476955 (3 pages) | Cited 25 times

Online Publication Date: 7 May 2002

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Frequency-tunable radiation from the free electron laser FELIX was used to excite neutral phosphorus and bismuth donors embedded in bulk monocrystalline silicon. Lasing at terahertz frequencies has been observed at liquid helium temperature while resonant pumping of odd parity impurity states. The threshold was about two orders of magnitude below the value for photoionization pumping. The influence of nonequilibrium intervalley TO phonons on the population of excited Bi impurity states is discussed. © 2002 American Institute of Physics.
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78.45.+h Stimulated emission
71.55.Cn Elemental semiconductors
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Thermodynamic properties of highly undercooled liquid TiAl alloy

N. Wang and B. Wei

Appl. Phys. Lett. 80, 3515 (2002); http://dx.doi.org/10.1063/1.1478777 (3 pages) | Cited 6 times

Online Publication Date: 7 May 2002

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The specific heat of an undercooled liquid TiAl alloy was measured by an electromagnetic levitation drop calorimeter and the related thermodynamic properties, difference in Gibbs free energy and change in entropy are calculated based on the experimental results and some well known models. Under the containerless processing condition, the liquid alloy was undercooled by up to 219 K (0.122TL). The change in enthalpy shows a linear relationship with the temperature and a nearly constant specific heat was determined even though this alloy was undercooled far below its liquidus temperature. The calculated results of the thermodynamic properties reveal that even though semiquantitative models fit with the experimental curve of the difference in Gibbs free energy well, they lead to different degrees of deviation in the entropy difference calculation. © 2002 American Institute of Physics.
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65.20.-w Thermal properties of liquids
81.05.Bx Metals, semimetals, and alloys
61.25.Mv Liquid metals and alloys
81.30.Bx Phase diagrams of metals, alloys, and oxides
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Optical properties of ZnO thin films: Ion layer gas reaction compared to sputter deposition

M. Rebien, W. Henrion, M. Bär, and Ch.-H. Fischer

Appl. Phys. Lett. 80, 3518 (2002); http://dx.doi.org/10.1063/1.1479211 (3 pages) | Cited 15 times

Online Publication Date: 7 May 2002

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Zinc oxide films prepared by the recently developed ion layer gas reaction (ILGAR) technique and by rf magnetron sputtering are compared with respect to their linear optical properties. Spectral ellipsometry as well as reflectance and transmittance measurements in the UV-visible-near infrared range were employed to deduce the complex refractive index. The band gap energy, Urbach energy, and packing density were determined. The results are compared to literature data of single crystals and thin films. © 2002 American Institute of Physics.
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78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.30.Fs III-V and II-VI semiconductors
78.40.Fy Semiconductors
81.15.Cd Deposition by sputtering
71.20.Nr Semiconductor compounds

Influence of GaN domain size on the electron mobility of two-dimensional electron gases in AlGaN/GaN heterostructures determined by x-ray reflectivity and diffraction

Zhenyang Zhong, O. Ambacher, A. Link, V. Holy, J. Stangl, R. T. Lechner, T. Roch, and G. Bauer

Appl. Phys. Lett. 80, 3521 (2002); http://dx.doi.org/10.1063/1.1479206 (3 pages) | Cited 13 times

Online Publication Date: 7 May 2002

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X-ray reflectivity and diffraction measurements were performed on Ga-face AlGaN/GaN heterostructures to determine the influence of interface roughness scattering and GaN domain boundaries scattering on the electron mobility of polarization induced two-dimensional electron gases. From simulations of the specular reflectivity, the root-mean-square roughness of the AlGaN/GaN interfaces was obtained. In reciprocal space maps, laterally elongated streaks passing through the Bragg peaks have been observed, which are attributed to column-like domains in the GaN buffer layers. The relationship between electron mobility measured by Hall effect and the interface roughness on one hand, and the column domain size on the other hand, demonstrates that the interface roughness scattering is not limiting the electron mobility, whereas the transport properties of the two-dimensional electron gas degrade with decreasing size of columnar domains in the GaN layer. © 2002 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.35.Ct Interface structure and roughness
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.20.At Surface states, band structure, electron density of states

Microscopic correlation of redshifted luminescence and surface defects in thick InxGa1−xN layers

F. Bertram, S. Srinivasan, L. Geng, F. A. Ponce, T. Riemann, and J. Christen

Appl. Phys. Lett. 80, 3524 (2002); http://dx.doi.org/10.1063/1.1479199 (3 pages) | Cited 12 times

Online Publication Date: 7 May 2002

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A direct correlation between the structural and luminescence properties of thick InxGa1−xN layers has been achieved on a microscopic scale using highly spatially resolved cathodoluminescence. Surface roughening is typically observed in growth by metalorganic vapor phase epitaxy of thick InxGa1−xN layers for x⩾0.1. Although the film remains highly planar, craters and protrusions appear on the surface. These surface defects are associated with redshifted luminescence indicative of indium segregation, and are related to threading dislocations in the films. © 2002 American Institute of Physics.
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68.35.Dv Composition, segregation; defects and impurities
81.05.Ea III-V semiconductors
68.55.A- Nucleation and growth
78.66.Fd III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.60.Hk Cathodoluminescence, ionoluminescence
64.75.-g Phase equilibria

Separation of optical anisotropies by angular dependent reflection anisotropy spectroscopy

B. F. Macdonald and R. J. Cole

Appl. Phys. Lett. 80, 3527 (2002); http://dx.doi.org/10.1063/1.1478784 (3 pages) | Cited 14 times

Online Publication Date: 7 May 2002

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Double rubbing of polymer films, which finds applications in modern liquid crystal devices, has been investigated using reflection anisotropy spectroscopy (RAS) and atomic force microscopy. A method of gauging the relative strength of rubbing in two different directions, based upon the dependence of observed RAS signals on the sample azimuthal angle, has been found. Angular dependent measurements are shown to be a useful extension of the standard technique by allowing angular dependent sources of optical anisotropy to be separated experimentally. © 2002 American Institute of Physics.
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78.66.Qn Polymers; organic compounds
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
78.20.Fm Birefringence
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Fluorine interaction with point defects, boron, and arsenic in ion-implanted Si

Ali Mokhberi, Reza Kasnavi, Peter B. Griffin, and James D. Plummer

Appl. Phys. Lett. 80, 3530 (2002); http://dx.doi.org/10.1063/1.1479458 (3 pages) | Cited 23 times

Online Publication Date: 7 May 2002

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The role of fluorine in suppressing boron diffusion was investigated by utilizing a buried dopant marker to monitor the interaction of fluorine with interstitials. A boron spike with a peak concentration of 1.2×1018 cm−3 followed by 500 nm of undoped silicon was grown in a low pressure chemical vapor deposition furnace. The wafers were then preamorphized and implanted with either B, B and F, BF2, As, As and F, or F, respectively. Following the implants, the samples were rapid thermal annealed (RTA) at 1050 °C for very short times (spike). The use of preamorphization allows the chemical effect of fluorine to be analyzed independently of implant damage, and the buried layer functions as an indicator of point defect (in this case Si self-interstitial) perturbation. As expected, secondary ion mass spectroscopy shows that the presence of fluorine retards the diffusion of boron. In addition, the retained fluorine dose after the RTA is highest in the boron-implanted samples. In all samples the buried layer has diffused by the same amount, indicating that there is no change to the silicon self-interstitial population due to fluorine. These results suggest that fluorine has a chemical effect, and retards boron diffusion by mainly bonding with boron. © 2002 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
61.72.uf Ge and Si
61.72.S- Impurities in crystals
66.30.J- Diffusion of impurities
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing

Magneto-thermal shape memory effect in Ni–Mn–Ga

N. Glavatska, I. Glavatsky, G. Mogilny, and V. Gavriljuk

Appl. Phys. Lett. 80, 3533 (2002); http://dx.doi.org/10.1063/1.1478130 (3 pages) | Cited 4 times

Online Publication Date: 7 May 2002

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A way to produce shape memory in Ni–Mn–Ga alloys is proposed based on the combined action of the magnetic field and heating. A sample is magnetized under applied magnetic field, which results in the magnetic-field-induced strain caused by the reorientation of martensitic domains so that the tetragonal axis c (axis of easy magnetization) is oriented in direction of the applied field. Thereafter the field is switched off and the sample is heated above the Curie temperature and cooled to the start temperature of the experiment, which leads to the full recovery of the size and structure existing before the action of magnetic field. This effect is explained based on the data of x-ray diffraction studies. © 2002 American Institute of Physics.
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81.30.Kf Martensitic transformations
75.80.+q Magnetomechanical effects, magnetostriction
81.05.Bx Metals, semimetals, and alloys
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
64.70.K- Solid-solid transitions
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Far-infrared absorption in Sb-doped Ge epilayers near the metal–insulator transition

Jordana Bandaru, Jeffrey W. Beeman, and Eugene E. Haller

Appl. Phys. Lett. 80, 3536 (2002); http://dx.doi.org/10.1063/1.1479203 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2002

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Epitaxial germanium layers doped near the metal–insulator transition were grown by liquid phase epitaxy from a Pb melt. Far-infrared absorption was measured between ∼20 cm−1 and 150 cm−1. Linear optical absorption coefficients were determined for Ge:Sb in the doping range of 9.0×1014 cm−3<ND<6.7×1016 cm−3. The peak absorption was found to increase linearly with dopant concentration as expected. The absorption at ∼50 cm−1 increased superlinearly with Sb concentration as a result of impurity banding. The optimal Sb concentration for extended far-infrared photoconductive response (λ>200 μm) in blocked impurity band detectors is discussed. © 2002 American Institute of Physics.
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78.66.Db Elemental semiconductors and insulators
78.30.Am Elemental semiconductors and insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.61.Cw Elemental semiconductors
71.30.+h Metal-insulator transitions and other electronic transitions
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Photoluminescence study of hydrogen passivation in InAs1−xNx/InGaAs single-quantum well on InP

Y. Y. Ke, M. H. Ya, Y. F. Chen, J. S. Wang, and H. H. Lin

Appl. Phys. Lett. 80, 3539 (2002); http://dx.doi.org/10.1063/1.1476383 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2002

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It is well known that nitrogen incorporation into III–V compounds will degrade the quality of materials. In this letter, we show that the incorporation of atomic hydrogen into InAsN/InGaAs quantum wells can effectively passivate defects and lead to enhancement of photoluminescence intensity near the band edge. After hydrogenation, the change of the optical properties is quite different from that of the annealing with nitrogen treatment. For instance, the linewidth becomes wider after hydrogenation, while the linewidth is narrower after nitrogen annealing. Through a detailed study of the photoluminescence spectra, we show that the passivation of defect bonds is the main reason for the improved optical behavior for hydrogenation, while the interdiffusion is responsible for the change after nitrogen annealing. © 2002 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.67.De Quantum wells
61.72.Cc Kinetics of defect formation and annealing
68.65.Fg Quantum wells
66.30.Ny Chemical interdiffusion; diffusion barriers
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