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11 Aug 1997

Volume 71, Issue 6, pp. 729-854

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Study of surface-emitted stimulated emission in GaN

S. Bidnyk, T. J. Schmidt, G. H. Park, and J. J. Song

Appl. Phys. Lett. 71, 729 (1997); http://dx.doi.org/10.1063/1.119627 (3 pages) | Cited 13 times

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We report the results of a study of spatially resolved surface-emitted stimulated emission in GaN epilayer samples under conditions of strong optical pumping. We observe that even at excitation powers near the damage threshold, no surface-emitted stimulated emission occurs from samples with a high quality GaN epilayer. In parts of the samples with inferior surface quality, we show that stimulated emission comes from cracks, burned spots, and other imperfections, and is due to the scattering of a photon flux propagating parallel to the surface. Our results suggest that these defects are effective scattering centers and can severely affect the accuracy of optical gain measurements. © 1997 American Institute of Physics.
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78.45.+h Stimulated emission
68.35.B- Structure of clean surfaces (and surface reconstruction)

Organic–inorganic dielectric multilayer systems as high reflectivity distributed Bragg reflectors

A. Convertino, A. Valentini, T. Ligonzo, and R. Cingolani

Appl. Phys. Lett. 71, 732 (1997); http://dx.doi.org/10.1063/1.119628 (3 pages) | Cited 18 times

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Unprecedentedly high reflectivity distributed Bragg reflectors consisting of fluorocarbon polymer (CFx) and high refractive index inorganic oxide multilayers have been fabricated by means of assisted ion-beam sputtering at room temperature. Multilayer stacks consisting of a CFx/TiOx and CFx/HfOx pairs exhibit reflectivities larger than 98% in the infrared and ultraviolet spectral region, respectively. The superior wide tunability and the high efficiency, with respect to inorganic–inorganic multilayers is due to the exceptionally low refractive index of the fluorcarbon polymer (n ≃ 1.35) on a very large spectral region (300–2000 nm). © 1997 American Institute of Physics.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Jk Polymers and organics
81.15.Cd Deposition by sputtering
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Observation of room-temperature laser emission from type III InAs/GaSb multiple quantum well structures

A. N. Baranov, N. Bertru, Y. Cuminal, G. Boissier, C. Alibert, and A. Joullié

Appl. Phys. Lett. 71, 735 (1997); http://dx.doi.org/10.1063/1.119629 (3 pages) | Cited 27 times

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Multiple quantum well InAs/GaSb laser heterostructures with type III (type II broken gap) band alignment in the active region have been grown by molecular beam epitaxy. Intense electroluminescence was observed at room temperature (RT) with peak emission wavelengths in the range 1.95–3.4 μm. RT lasing has been achieved at 1.98 and 2.32 μm for the structures with 6 and 12 Å thick InAs quantum wells, respectively. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.60.Fi Electroluminescence

Use of guided spontaneous emission of a semiconductor to probe the optical properties of two-dimensional photonic crystals

D. Labilloy, H. Benisty, C. Weisbuch, T. F. Krauss, R. Houdré, and U. Oesterle

Appl. Phys. Lett. 71, 738 (1997); http://dx.doi.org/10.1063/1.119630 (3 pages) | Cited 41 times

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We describe an experimental setup, which allows assessing the optical properties of two-dimensional photonic crystals combined with a waveguide geometry, and etched into a light-emitting (GaAs/InGaAs) semiconductor. By means of a guiding layer, the spontaneous emission of the material is used as a built-in source to probe the properties of the etched microstructure, conveniently compared to the usual measurement schemes. We show polarized transmission and coefficients largely depending on the photonic crystal orientation. © 1997 American Institute of Physics.
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42.50.-p Quantum optics
78.66.Fd III-V semiconductors

Strong polarization selectivity in 780-nm vertical-cavity surface-emitting lasers grown on misoriented substrates

Young-Gu Ju, Yong-Hee Lee, Hyun-Kuk Shin, and Il Kim

Appl. Phys. Lett. 71, 741 (1997); http://dx.doi.org/10.1063/1.119631 (3 pages) | Cited 6 times

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We report that the 780 nm quantum well vertical-cavity surface-emitting lasers (VCSELs) grown on a 2° off misoriented (001) substrate toward (111)A exhibit a high polarization suppression ratio over a few hundred. The main polarization is always along the [−110] direction for all the lasers over the entire operating currents. To understand the physical origin of this polarization selectivity, the gain/loss difference between two competing polarization modes in VCSELs is investigated by measuring the subthreshold spectral linewidth. The obtained modal gain/loss difference is about 3.0 cm−1, which is sufficiently large for polarization stabilization and amounts to 4% of the threshold modal gain. Comparison with the subthreshold measurement and previous theoretical work shows significant discrepancy, which implies the possibility of other polarization selection mechanisms inducing such large gain/loss differences in 780 nm quantum wells grown on a misoriented substrate. In addition, it is found that the 780 nm VCSEL made of a bulk active medium grown on a misoriented substrate also shows a high polarization selectivity as quantum well lasers. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Mapping the confined optical field in a microcavity via the emission from a conjugated polymer

D. G. Lidzey, D. D. C. Bradley, M. A. Pate, J. P. R. David, D. M. Whittaker, T. A. Fisher, and M. S. Skolnick

Appl. Phys. Lett. 71, 744 (1997); http://dx.doi.org/10.1063/1.119632 (3 pages) | Cited 11 times

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The distribution of a confined optical field within a microcavity was determined using a thin layer of the fluorescent polymer PPV as a probe of the local-field amplitude. It is shown that the photoluminescence emission intensity from the cavity is a function of the axial position of the polymer, and confirms that a microcavity can be used to control spontaneous emission. © 1997 American Institute of Physics.
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78.55.Kz Solid organic materials
42.70.Jk Polymers and organics
42.50.-p Quantum optics
42.79.-e Optical elements, devices, and systems

Experimental study of integrated-optics microcavity resonators: Toward an all-optical switching device

F. C. Blom, D. R. van Dijk, H. J. W. M. Hoekstra, A. Driessen, and Th. J. A. Popma

Appl. Phys. Lett. 71, 747 (1997); http://dx.doi.org/10.1063/1.119633 (3 pages) | Cited 41 times

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An integrated all-optical switch based on a high-Q nonlinear cylindrical microcavity resonator is proposed. The switch consists of single mode planar waveguides that allow coupling light in and out to a microresonator, exhibiting whispering gallery modes. Due to the high Q factor and the small dimensions, fast switching at low power is feasible for devices based on presently available nonlinear polymers as the active material. In this approach, the transmission of an integrated optical waveguide close to a microcavity has been measured and related to the resonances of the cylindrical microcavity. © 1997 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Gn Optical waveguides and couplers
42.65.Wi Nonlinear waveguides
42.70.Jk Polymers and organics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Mode selective polymer channel waveguide defined by the photoinduced change in birefringence

Osamu Watanabe, Masaaki Tsuchimori, Akane Okada, and Hiroshi Ito

Appl. Phys. Lett. 71, 750 (1997); http://dx.doi.org/10.1063/1.119634 (3 pages) | Cited 16 times

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A transverse electric (TE) mode selective polymer waveguide was fabricated by a photobleaching process using a urethane–urea copolymer. The output power of the TE modes through the waveguide was higher than that of the transverse magnetic (TM) modes, when the TE and TM modes were excited equally, the TE mode to TM mode extinction ratio being 27 dB. Mode selectivity was explained by the following relation of the refractive index: the refractive index for the TE modes in the core region was higher than that in the cladding region, while the refractive index for the TM modes in the core was lower than that in the cladding. This relation was attained by the photoinduced change in birefringence of the polymer layer. © 1997 American Institute of Physics.  
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42.70.Jk Polymers and organics
42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers
78.20.Fm Birefringence
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.70.Gi Light-sensitive materials
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Unidirectional radiation of widely tunable THz wave using a prism coupler under noncollinear phase matching condition

Kodo Kawase, Manabu Sato, Koichiro Nakamura, Tetsuo Taniuchi, and Hiromasa Ito

Appl. Phys. Lett. 71, 753 (1997); http://dx.doi.org/10.1063/1.119635 (3 pages) | Cited 47 times

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A widely tunable THz wave has been parametrically generated and reported recently by us utilizing a LiNbO3 crystal with a monolithic grating coupler under a noncollinear phase matching condition. However, the output direction of the THz wave is strongly dependent on the generated frequency due to the nature of noncollinear phase matching, as well as the grating coupler. In this letter, a novel method for THz coupling is proposed using a low dispersion prism to eliminate almost completely the THz beam deflection for the entire tuning range. The unidirectional THz wave radiation was confirmed theoretically and experimentally for the range of 1–2 THz. © 1997 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Yj Optical parametric oscillators and amplifiers
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
42.70.Mp Nonlinear optical crystals
42.79.Bh Lenses, prisms and mirrors

Ion exchange in potassium titanyl phosphate

K. Daneshvar, E. A. Giess, A. M. Bacon, D. G. Dawes, L. A. Gea, and L. A. Boatner

Appl. Phys. Lett. 71, 756 (1997); http://dx.doi.org/10.1063/1.119636 (3 pages) | Cited 6 times

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Ion-exchange processes in potassium titanyl phosphate (KTiOPO4 or KTP) single crystal immersed in Rb, Rb–Ba, Rb–Sr nitrate molten solutions have been investigated by using Rutherford backscattering depth-profile analysis. The depth to which Rb-ion exchange occurred in KTP was found to be sensitive to the presence of as little as 0.1% of a Ba impurity in a molten solution of rubidium nitrate. The addition of impurities such as Ba significantly increased the ion-exchange depth of Rb in KTP, and the Rb distribution after ion exchange. Using pure RbNO3, however, the depth of the Rb ion exchange was relatively shallow, and the Rb surface concentration was measurably greater at the minus than at the plus polar-axis faces of the crystal. These findings are relevant to the application of ion-exchange techniques to the fabrication of optical waveguides on KTP substrates. © 1997 American Institute of Physics.
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82.30.Hk Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)
42.79.Gn Optical waveguides and couplers
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
66.30.H- Self-diffusion and ionic conduction in nonmetals

Photostimulated luminescence in Eu2+-doped fluoroaluminate glasses

Jianrong Qiu, Y. Shimizugawa, Y. Iwabuchi, and K. Hirao

Appl. Phys. Lett. 71, 759 (1997); http://dx.doi.org/10.1063/1.119637 (3 pages) | Cited 41 times

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Photostimulated luminescence phenomenon was observed in a fluoroaluminate glass doped with Eu2+. When the x-ray irradiated glass was excited by a He–Ne laser (633 nm), photostimulated luminescence at 400 nm due to the 5d–4f transition of Eu2+ ions was observed. X-ray absorption spectra showed that a part of Eu2+ converted to Eu3+ upon the irradiation of x-ray. By comparing with the investigations on photostimulable luminescence phosphor BaFBr:Eu2+, the luminescence appears to result from the photostimulated recombination of holes and electrons at traps, which leave electrons in a long-lived excited state. © 1997 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
61.80.Cb X-ray effects
78.70.Dm X-ray absorption spectra
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Five-wavelength surface emitting laser diode array based on postgrowth adjustment of emission wavelength

A. Golshani, P. O. Kellermann, A. Köck, E. Gornik, and L. Korte

Appl. Phys. Lett. 71, 762 (1997); http://dx.doi.org/10.1063/1.119638 (3 pages) | Cited 3 times

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A five-wavelength surface emitting laser diode array based on surface mode emission is reported. The wavelength control is achieved by postgrowth adjustment of the surface structure. Wavelength spacing between laser groups is 1.1 nm in average and the wavelength reproducibility is ±0.13 nm. The total change in the emission wavelength over the array is 4.78 nm. The single array elements show single mode emission with a full width at half-maximum of 0.08 nm in average and a side mode suppression ratio up to 20 dB. This type of laser diode is of high interest for wavelength division multiplexing applications. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
68.35.B- Structure of clean surfaces (and surface reconstruction)

Reverse bias tuned multiple quantum well ridge guide laser with uniform frequency modulation response

X. Huang, A. J. Seeds, and J. S. Roberts

Appl. Phys. Lett. 71, 765 (1997); http://dx.doi.org/10.1063/1.119639 (2 pages) | Cited 2 times

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We report a multiple quantum well ridge guide laser tuned by the quantum confined Stark effect. In contrast to carrier-induced effect tuned lasers, the frequency modulation response of our laser is highly uniform (±0.7 dB) over the frequency range from 10 kHz to 100 MHz, and within ±2.5 dB from 5 kHz to 500 MHz, with the upper frequency parasitic capacitance limited. We predict that the response could be extended to over 20 GHz by using a low parasitic contacting structure. © 1997 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.)
42.60.Fc Modulation, tuning, and mode locking
78.20.Jq Electro-optical effects
42.79.Hp Optical processors, correlators, and modulators
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Evidence of nonuniform carrier distribution in multiple quantum well lasers

Hiroyuki Yamazaki, Akihisa Tomita, Masayuki Yamaguchi, and Yoshihiro Sasaki

Appl. Phys. Lett. 71, 767 (1997); http://dx.doi.org/10.1063/1.119640 (3 pages) | Cited 18 times

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Carrier distribution in multiple quantum well (MQW) lasers is studied by measuring laser wavelength. The MQW is designed to contain wells with different thicknesses. The MQW laser wavelength agreed with the transition wavelength of the wells near the p-clad layer at room temperature. At low temperatures, however, the laser wavelength corresponded to the thicker wells. The results imply that hole localization takes place at room temperature but disappears at low temperatures. This shows the invalidity of the conventional capture/escape model. The importance of the mean free path of unbound carriers is pointed out. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Cluster models for the photoabsorption of divalent defects in silicate glasses: Basis set and cluster size dependence

Boris B. Stefanov and Krishnan Raghavachari

Appl. Phys. Lett. 71, 770 (1997); http://dx.doi.org/10.1063/1.120422 (3 pages) | Cited 10 times

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The two lowest singlet excited states of divalent Si defects in silicate glasses are studied by ab initio methods. Excitation energies of 5.2 and 6.8 eV are obtained. Steady convergence to these values is shown with the increase in size both of the model cluster and of the basis set employed in the calculations. The results clearly demonstrate the viability of the quantum-chemical cluster approach for the study of local excitations in glass defects. © 1997 American Institute of Physics.
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78.40.Ha Other nonmetallic inorganics
61.43.Fs Glasses
71.10.Li Excited states and pairing interactions in model systems
61.72.Bb Theories and models of crystal defects
71.55.Jv Disordered structures; amorphous and glassy solids

Electron heating effects in diffusive metal wires

M. Henny, H. Birk, R. Huber, C. Strunk, A. Bachtold, M. Krüger, and C. Schönenberger

Appl. Phys. Lett. 71, 773 (1997); http://dx.doi.org/10.1063/1.119641 (3 pages) | Cited 26 times

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We have investigated the electron heating in metallic diffusive wires of varying length at liquid-helium temperature by measuring the electric noise. The local increase of the electron temperature can be essential already for small currents and is well described by a heat-diffusion equation for the electrons. Depending on the electron thermal conductance and the electron–phonon coupling in the wire, different length regimes are identified. The quantitative knowledge of the electron temperature is important for analysis of nonequilibrium effects involving current heating in mesoscopic wires. © 1997 American Institute of Physics.
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73.23.Ad Ballistic transport

Dislocation-free InSb grown on GaAs compliant universal substrates

F. E. Ejeckam, M. L. Seaford, Y.-H. Lo, H. Q. Hou, and B. E. Hammons

Appl. Phys. Lett. 71, 776 (1997); http://dx.doi.org/10.1063/1.119642 (3 pages) | Cited 52 times

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An innovative compliant GaAs substrate was formed by wafer bonding a 30 Å GaAs layer to a bulk GaAs crystal with a large angular misalignment inserted about their common normals. InSb epitaxial layers, which is about 15% lattice mismatched to GaAs, have been grown on both compliant substrates and conventional GaAs substrates. Transmission electron microscopy studies showed that the InSb films grown on the compliant substrates have no measurable threading dislocations, whereas the InSb films on the conventional GaAs substrates exhibited dislocation densities as high as 1011 cm−2. The observations made here suggest that the defect-free heteroepitaxial growth of exceedingly large lattice-mismatched crystals can be achieved with compliant universal substrates. © 1997 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Stress overshoot in stress-strain curves of Zr65Al10Ni10Cu15 metallic glass

Yoshihito Kawamura, Tsutomu Shibata, Akihisa Inoue, and Tsuyoshi Masumoto

Appl. Phys. Lett. 71, 779 (1997); http://dx.doi.org/10.1063/1.119643 (3 pages) | Cited 22 times

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The essential features of the stress overshoot in the stress-strain curves of Zr65Al10Ni10Cu15 (at. %) metallic glass that has a wide supercooled liquid region were revealed. The stress overshoot was dependent on temperature, strain rate, and stress relaxation. During the stretch, a change in strain rate gave rise to stress overshoot or undershoot which was sensitive to the variable quantities in the strain rate. © 1997 American Institute of Physics.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
61.43.Fs Glasses
81.40.Lm Deformation, plasticity, and creep

Tailored superlattices containing distinct oxide and oxycarbonate blocks grown by pulsed laser deposition

W. Prellier, B. Mercey, Ph. Lecoeur, J. F. Hamet, and B. Raveau

Appl. Phys. Lett. 71, 782 (1997); http://dx.doi.org/10.1063/1.119644 (3 pages) | Cited 7 times

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The synthesis of copper oxycarbonate superlattices comprised of two structural types that are observed in high Tc superconductors was achieved using the pulsed laser deposition (PLD) technique. These artificially layered materials consist of specific numbers of alternately stacked infinite layer SrCuO2 and oxycarbonate Ba2−xCaxCuO2CO3 blocks, and were grown on (110) NdGaO3 using two targets. From x-ray diffraction, it was found that several unit cells of SrCuO2 could be inserted between the layers of Ba2−xCaxCuO2CO3. These results demonstrate that a large series of new structures combining oxycarbonate with oxide components can be obtained using a multitarget PLD system. © 1997 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
74.78.Fk Multilayers, superlattices, heterostructures
81.15.Fg Pulsed laser ablation deposition
68.35.Ct Interface structure and roughness
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures

Optical investigation of growth mode of Ge thin films on Si(110) substrates

J. Arai, A. Ohga, T. Hattori, N. Usami, and Y. Shiraki

Appl. Phys. Lett. 71, 785 (1997); http://dx.doi.org/10.1063/1.119645 (3 pages) | Cited 10 times

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A unique growth mode of Ge on Si(110) substrates was clarified by photoluminescence (PL) spectroscopy. A spectral redshift and an increase of the relative no-phonon intensity were found for PL from the two-dimensional Ge layer on Si(110) compared to that on Si(100). These results likely arise from nonuniformity in the Ge layer thickness owing to the step-bunched Si(110) surface and resultant exciton localization. The two-dimensional to three-dimensional growth mode changeover was observed as evidenced by emergence of broad PL from Ge islands. In contrast to Ge on Si(100) PL from the wetting layer was found to show continuous redshift with increasing Ge coverage even after Ge island formation. © 1997 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Ap Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology

Hole intersubband relaxation in CdTe/CdMnTe quantum wells

J.-P. Likforman, A. Alexandrou, E. Vanelle, and J. Cibert

Appl. Phys. Lett. 71, 788 (1997); http://dx.doi.org/10.1063/1.119646 (3 pages)

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We report a direct measurement of the hole relaxation time in undoped CdTe/CdMnTe quantum wells. The internal piezoelectric field in a (111)-grown structure is screened by e1h1 and e1h2 excitons with different efficiency. Thus, the temporal evolution of the screened field, as monitored by the e1h1 exciton energy in a pump-probe transmission experiment, allows the determination of the e1h2−e1h1 relaxation time. We obtained a relaxation time of 15±5 ps for a splitting of 15 meV, smaller than the longitudinal-optical (LO) phonon energy. Deformation-potential scattering is too slow to explain this relaxation time which we attribute to hole-hole scattering and LO-phonon emission by e1h2 excitons acquiring enough kinetic energy. © 1997 American Institute of Physics.
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73.61.Ga II-VI semiconductors
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
75.50.Pp Magnetic semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
71.35.-y Excitons and related phenomena

Optical studies of very high-purity GaAs grown by metal–organic chemical-vapor deposition using a point-of-use arsine (AsH3) generator

Jan P. van der Ziel, Xuefei Tang, and Ralph Johnson

Appl. Phys. Lett. 71, 791 (1997); http://dx.doi.org/10.1063/1.119647 (3 pages) | Cited 4 times

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We describe low-temperature photoluminescence studies of high-purity epitaxial GaAs and GaAs/AlGaAs quantum wells grown in a low-pressure metal–organic chemical–vapor deposition (MOCVD) reactor using electrolytically generated AsH3 as the group V source material and trimethylgallium and trimethylaluminum as the group III sources. The use of on-site point-of-use generated AsH3, made using the electrolytic conversion of solid As source material, greatly improves the safety of the MOCVD growth process, since AsH3 is generated only as needed, and at any time only a small volume of AsH3 is present. The photoluminescence studies indicate that very high-purity GaAs and GaAs/AlGaAs quantum wells layers are obtained using this source of AsH3. The GaAs/AlGaAs material has been used for a variety of devices including photodetectors and low threshold vertical cavity surface emitting lasers. © 1997 American Institute of Physics.
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81.05.Ea III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Electron emission from disordered tetrahedral carbon

B. L. Weiss, A. Badzian, L. Pilione, T. Badzian, and W. Drawl

Appl. Phys. Lett. 71, 794 (1997); http://dx.doi.org/10.1063/1.119648 (3 pages) | Cited 15 times

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Electron field-emission tests have been performed on films grown by a modified microwave plasma assisted chemical vapor deposition diamond process. This modification includes the addition of N2 and O2 during the growth stage. Characterization of these films shows the presence of a disordered tetrahedral carbon structure. Raman spectroscopy indicates a disturbance in the cubic symmetry of the lattice and x-ray diffraction indicates a disordered tetrahedral structure. Field-emission testing indicate that current densities of 0.5 mA/cm2 can be obtained for applied fields of 5–8 V/μm. The results are explained in terms of a change in the band structure and the formation of electronic states in the band gap. © 1997 American Institute of Physics.
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79.70.+q Field emission, ionization, evaporation, and desorption
68.55.-a Thin film structure and morphology
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Reversible transition between InGaAs dot structure and InGaAsP flat surface

Kazunari Ozasa, Yoshinobu Aoyagi, Young Ju Park, and Lars Samuelson

Appl. Phys. Lett. 71, 797 (1997); http://dx.doi.org/10.1063/1.119649 (3 pages) | Cited 20 times

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We have studied the in situ modification of coherently grown InGaAs dots by interaction with phosphorus. By monitoring the intensity of reflection high-energy electron diffraction transmission spot, the in situ phosphorus (precracked PH3) supply on the InGaAs dots was examined at 480 °C. It was found that the phosphorus exposure induces a surface structure change from a dot structure to a flat surface. The change is caused by the replacement of arsenic in the dots by phosphorus, which reduces the strain between the InGaAs(P) dots and the GaAs substrate. By switching AsH3/PH3 beams in situ, a reversible transition of the surface structure between the InGaAs dot structure and the InGaAsP flat surface was observed. A transitional state between the dot structure and the flat surface was metastabilized by tuning the AsH3/PH3 beam ratio. The metastabilized surface was observed ex situ using a high-resolution scanning electron microscope. © 1997 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj III-V and II-VI semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology

Determination of the band-gap energy of Al1−xInxN grown by metal–organic chemical-vapor deposition

K. S. Kim, A. Saxler, P. Kung, M. Razeghi, and K. Y. Lim

Appl. Phys. Lett. 71, 800 (1997); http://dx.doi.org/10.1063/1.119650 (3 pages) | Cited 53 times

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Ternary AlInN was grown by metal–organic chemical-vapor deposition in the high Al composition regime. The band-gap energy of AlInN ternary was measured by optical absorption spectroscopy at room temperature. The band-gap energy of Al0.92In0.08N is 5.26 eV. The potential application of AlInN as a barrier material for GaN is also discussed. © 1997 American Institute of Physics.
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71.20.Nr Semiconductor compounds
78.40.Fy Semiconductors
78.66.Fd III-V semiconductors
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