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15 Sep 1997

Volume 71, Issue 11, pp. 1441-1585

Page 1 of 2 Pages Next Page | Jump to Page

Fabrication of photonic crystals by deep x-ray lithography

G. Feiertag, W. Ehrfeld, H. Freimuth, H. Kolle, H. Lehr, M. Schmidt, M. M. Sigalas, C. M. Soukoulis, G. Kiriakidis, T. Pedersen, J. Kuhl, and W. Koenig

Appl. Phys. Lett. 71, 1441 (1997); http://dx.doi.org/10.1063/1.120431 (3 pages) | Cited 58 times

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We have developed a new microfabrication technique for the construction of three-dimensional photonic crystals. In particular, we used multiple tilted x-ray lithography exposures in order to construct structures with photonic band gaps in the infrared region. First polymethylmethacrylate (PMMA) resist layers with a thickness of 500 μm were irradiated, then the holes in the resist structure were filled with preceramic polymer and subsequent pyrolysis converts the preceramic polymer into a SiCN ceramic. Theoretical results with fitted values of the dielectric constant are in good agreement with the transmission measurements. © 1997 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.86.+b Optical workshop techniques

GaAs/AlGaAs ridge lasers with etched mirrors formed by an inductively coupled plasma reactor

S. C. Horst, S. Agarwala, O. King, J. L. Fitz, and S. D. Smith

Appl. Phys. Lett. 71, 1444 (1997); http://dx.doi.org/10.1063/1.119931 (2 pages) | Cited 8 times

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Etched mirrors for semiconductor lasers are necessary for optoelectronic integrated circuit applications. This letter reports on the use of an inductively coupled plasma (ICP) reactor to create etched mirrors on GaAs/AlGaAs ridge lasers. Etch chemistries consisting of boron trichloride and chlorine were used to achieve both smooth and vertical mirror surfaces. Optical measurements indicate that devices fabricated with ICP etched mirrors are comparable to devices formed by cleaved mirrors. © 1997 American Institute of Physics.
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81.05.Ea III-V semiconductors
42.55.Px Semiconductor lasers; laser diodes
42.79.Bh Lenses, prisms and mirrors
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
85.60.-q Optoelectronic devices

Soft x-ray circular polarizer using magnetic circular dichroism at the Fe L3 line

J. B. Kortright, S.-K. Kim, T. Warwick, and N. V. Smith

Appl. Phys. Lett. 71, 1446 (1997); http://dx.doi.org/10.1063/1.119932 (3 pages) | Cited 11 times

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Linearly polarized soft x-rays are converted to elliptical polarization at the Fe L3 line (707 eV) using magnetic circular dichroism (MCD) on transmission through thin Fe films. A linear polarizer measured the transmitted polarization at different incidence angles to vary as expected from a model for in-plane magnetization, and also to exhibit a weak MCD effect at normal incidence interpreted to originate from perpendicular interface anisotropy. An MCD signal from a downstream Fe film was produced by switching the helicity of x-rays transmitted through an upstream circular polarizer. Practical considerations for optimizing the production of circular polarization are discussed, and synchrotron radiation applications using these circular polarizing filters are suggested.
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07.85.-m X- and γ-ray instruments
78.66.Bz Metals and metallic alloys
78.20.Ls Magneto-optical effects
87.64.K- Spectroscopy
42.25.Ja Polarization
42.25.Lc Birefringence
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy

Improved performance of oxide-confined vertical-cavity surface-emitting lasers using a tunnel injection active region

D. L. Huffaker and D. G. Deppe

Appl. Phys. Lett. 71, 1449 (1997); http://dx.doi.org/10.1063/1.119933 (3 pages) | Cited 12 times

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Data are presented on vertical-cavity surface-emitting lasers that use tunneling for injection of electrons into a quantum well active region. The tunneling injection scheme increases the electronic confinement and improves the lasing performance for small active areas. A lasing threshold of 36 μA with a slope efficiency of 23% is achieved for a 2.5 μm device, and a 52% slope efficiency is achieved for a 4 μm device with a 92 μA threshold. © 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.)

Free-space transient magneto-optic sampling

J. A. Riordan, F. G. Sun, Z. G. Lu, and X.-C. Zhang

Appl. Phys. Lett. 71, 1452 (1997); http://dx.doi.org/10.1063/1.119934 (3 pages) | Cited 6 times

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We demonstrate a free-space magneto-optic sampling system to measure the transient magnetic component of a freely propagating terahertz beam. Preliminary results using two magneto-optic sensors are presented. A detection sensitivity of 10−7 T of the picosecond magnetic field in a standard pump/probe configuration is obtained. In the current orthogonal geometry, a 13 ps risetime of the free-space magneto-optic signal is measured. A temporal resolution limited only by the material spin relaxation time in a velocity-matched geometry is anticipated. © 1997 American Institute of Physics.  
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.70.Sq Magnetooptical devices
06.60.Jn High-speed techniques (microsecond to femtosecond)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
78.20.Ls Magneto-optical effects

Reconfigurable optical properties in InGaN/GaN quantum wells

I. K. Shmagin, J. F. Muth, R. M. Kolbas, M. P. Mack, A. C. Abare, S. Keller, L. A. Coldren, U. K. Mishra, and S. P. DenBaars

Appl. Phys. Lett. 71, 1455 (1997); http://dx.doi.org/10.1063/1.119935 (3 pages) | Cited 11 times

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Reconfigurable optical properties were studied in InGaN/GaN multiple quantum well (MQW) structures. It was observed that a short time exposure to a high intensity ultraviolet light results in long term, but reversible changes of the optical properties of InGaN/GaN MQW samples. The photoinduced changes can be observed using an optical microscope under low intensity ultraviolet light and are visible as a high contrast pattern. The retention time at room temperature for 12 and 20 MQW samples was longer than five days and four weeks, respectively. The effect was studied at room and cryogenic temperatures. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
42.79.Vb Optical storage systems, optical disks
42.70.Gi Light-sensitive materials
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
42.70.Ln Holographic recording materials; optical storage media

Internal laser cooling of Yb3+-doped glass measured between 100 and 300 K

C. E. Mungan, M. I. Buchwald, B. C. Edwards, R. I. Epstein, and T. R. Gosnell

Appl. Phys. Lett. 71, 1458 (1997); http://dx.doi.org/10.1063/1.120441 (3 pages) | Cited 21 times

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Laser cooling of a solid can occur when it emits photons of higher mean energy than those it absorbs. Photothermal deflection spectra of a fluorozirconate glass (ZBLANP) doped with 1 wt% Yb3+ show cooling in an internal volume of the sample at temperatures between 100 and 300 K. A cooling efficiency of ∼1% relative to the absorbed laser power at 1015 nm is maintained at all temperatures. The results show promise for solid-state cooling of bulk materials at temperatures below 150 K.© 1997 American Institute of Physics.
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65.90.+i Other topics in thermal properties of condensed matter (restricted to new topics in section 65)
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
07.60.-j Optical instruments and equipment
61.82.Ms Insulators

Collapse and revival of exciton–polariton oscillation in a semiconductor microcavity

H. Cao, S. Jiang, S. Machida, Y. Takiguchi, and Y. Yamamoto

Appl. Phys. Lett. 71, 1461 (1997); http://dx.doi.org/10.1063/1.119936 (3 pages) | Cited 6 times

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We measured temporal evolution of the coherent emission from a semiconductor microcavity by a very sensitive ac balanced homodyne detection system. We observed collapse and revival of the exciton–polariton oscillation due to a three-mode beating. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
73.61.Ey III-V semiconductors
71.35.Gg Exciton-mediated interactions
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
78.55.Cr III-V semiconductors

Shrinkage-corrected volume holograms based on photopolymeric phase media for surface-normal optical interconnects

Chunhe Zhao, Jian Liu, Zhenhai Fu, and Ray T. Chen

Appl. Phys. Lett. 71, 1464 (1997); http://dx.doi.org/10.1063/1.119937 (3 pages) | Cited 13 times

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The film shrinkage effect of photopolymeric phase media failed to provide the desired volume holograms for point-to-point optical interconnects. In this letter, we report a compensation method to physically correct the shrinkage effect that resulted from the holographic recording and the postbaking. Dupont photopolymer HRF-600X001 is studied. The correction of the Bragg diffraction angle shift of 1°21′, which is induced by a 5.25% film shrinkage, is successfully demonstrated with the surface-normal configuration. A shrinkage-corrected volume hologram with 80% diffraction efficiency is experimentally confirmed. The methodology reported herein is applicable to other phase media when the associated film shrinkage data are experimentally determined. © 1997 American Institute of Physics.
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42.40.Eq Holographic optical elements; holographic gratings
42.70.Ln Holographic recording materials; optical storage media
42.70.Jk Polymers and organics
42.82.Ds Interconnects, including holographic interconnects
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.40.Pa Volume holograms
42.40.My Applications
42.40.Lx Diffraction efficiency, resolution, and other hologram characteristics

A spatially resolved optical emission sensor for plasma etch monitoring

Steven Shannon, James Paul Holloway, Kirk Flippo, and M. L. Brake

Appl. Phys. Lett. 71, 1467 (1997); http://dx.doi.org/10.1063/1.119938 (2 pages) | Cited 8 times

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A spatially resolved optical emission spectroscopy sensor has been developed, and the resulting reconstructed radial emission profiles from an ArI and ArII line compare well with Ar sputter etch uniformity profiles. The new sensor collects light from a wedge shaped field of view, and is rotated around a single collection point in order to observe the entire plasma through a relatively small viewpoint. © 1997 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.Cf Surface cleaning, etching, patterning
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
32.70.Jz Line shapes, widths, and shifts
32.30.Jc Visible and ultraviolet spectra
07.60.-j Optical instruments and equipment

Room temperature observation of single electron tunneling effect in self-assembled metal quantum dots on a semiconductor substrate

Kang-Ho Park, Jeong Sook Ha, Wan Soo Yun, Mincheol Shin, Kyoung-Wan Park, and El-Hang Lee

Appl. Phys. Lett. 71, 1469 (1997); http://dx.doi.org/10.1063/1.119939 (3 pages) | Cited 38 times

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We report on the observation of room-temperature single electron tunneling phenomena in a metal-insulator-metal-semiconductor double-junction structure. The nanosized Ag dots were self-assembled on a Sb-terminated Si(100) surface, and the Coulomb gap and staircases were observed in the local current–voltage (I–V) measurements using scanning tunneling microscopy. The I–V characteristics exhibiting the single electron tunneling behavior vary significantly with the variation of the measurement position within the same Ag droplet. These phenomena are well described by the tip-dot(Ag)-Si double-junction picture. © 1997 American Institute of Physics.
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73.23.Hk Coulomb blockade; single-electron tunneling
73.40.Ns Metal-nonmetal contacts
73.61.At Metal and metallic alloys
73.40.Gk Tunneling

Observation of multiple electrically induced phase transitions and a decoupling of the induced strain and polarization in Sn-modified lead zirconate titanate

Donald Forst, Jie-Fang Li, and Dwight Viehland

Appl. Phys. Lett. 71, 1472 (1997); http://dx.doi.org/10.1063/1.119940 (3 pages) | Cited 3 times

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Studies of Pb0.98Nb0.02[(Zr1−xSnx)0.97Ti3]1−zO3 (PZST x/3/2) were performed for 0<x<0.20 by electrically induced polarization and strain methods. Maximum electrically induced strains (ϵ) and polarizations (P) were found in the compositional range around x = 0.15, where ferroelectric and antiferroelectric regions coexisted. In addition, these studies demonstrated evidence for two electrically induced phase transitions: (i) an antiferroelectric–ferroelectric near 40 kV/cm, and (ii) a secondary ferroelectric–ferroelectric near 60–80 kV/cm. The dominate contribution to ϵ was associated with the secondary transition, whereas the dominate contribution to P was associated with the first. © 1997 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.B- Phase transitions and Curie point
77.22.Ej Polarization and depolarization
77.65.Bn Piezoelectric and electrostrictive constants
61.66.Bi Elemental solids
61.66.Dk Alloys

Huge thermopower of porous Y2O3

K. Koumoto, W. S. Seo, and S. Ozawa

Appl. Phys. Lett. 71, 1475 (1997); http://dx.doi.org/10.1063/1.119941 (2 pages) | Cited 11 times

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Porous Y2O3 ceramic was found to show huge thermopower values up to −50 mV/K at 900–1000 K in vacuum, but not in air. Such huge thermopowers may be generated by the electron gas emitted from the internal surfaces of the pores and are associated with some unknown effects. The nondimensional thermoelectric figure of merit, ZT, of this porous ceramic was as large as ∼ 0.95 at ∼ 950 K, and hence, it can be used as a thermoelectric material. © 1997 American Institute of Physics.
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72.20.Pa Thermoelectric and thermomagnetic effects
72.80.Sk Insulators

Self-texturing of nitrogenated amorphous carbon thin films for electron field emission

S. R. P. Silva, Gehan A. J. Amaratunga, and J. R. Barnes

Appl. Phys. Lett. 71, 1477 (1997); http://dx.doi.org/10.1063/1.119975 (3 pages) | Cited 50 times

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The electron field-emission process for nitrogenated amorphous carbon (a-C:H:N) thin films deposited using a magnetically confined hydrocarbon plasma is examined. The morphology of the films obtained using an atomic force microscope is compared to the field-emission properties. Beyond a chemical composition of 14 at. % nitrogen, the mirror smooth a-C:H:N films become self-texturing, and multiple “domelike” cathodes of nanometer scale are observed. The dimensions of these “domelike” cathodes varies with time, and after a 15 min deposition have dimensions of approximately 50 nm base diameter and 20 nm in height. When the electronic field emission of these textured films (N content 15 at. %) are measured, there is an enhancement in the emitted current density of ∼ 2 orders of magnitude at an electric field of 20 V/μm, in comparison to the untextured films with a nitrogen content of 11 at. %. © 1997 American Institute of Physics.
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81.05.ub Fullerenes and related materials
79.70.+q Field emission, ionization, evaporation, and desorption
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology

Growth and structural characterization of highly oriented sputter-deposited (111), (110), and (100) Co/Cu superlattices

David J. Smith, A. R. Modak, T. A. Rabedeau, and S. S. P. Parkin

Appl. Phys. Lett. 71, 1480 (1997); http://dx.doi.org/10.1063/1.119942 (3 pages) | Cited 7 times

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Highly oriented, sputter-deposited (111), (110), and (100) Co/Cu superlattices have been grown simultaneously on substrates of Al2O3 (sapphire), MgO (110), and (100), respectively, using thin seed layers of Pt or Pd deposited at ∼ 500 °C. High-resolution electron microscopy and x-ray scattering demonstrate that the films are epitaxial and of excellent crystallinity. © 1997 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.-a Thin film structure and morphology
81.05.Bx Metals, semimetals, and alloys
81.15.Cd Deposition by sputtering
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Effects of photo-oxidation on conjugated polymer films

G. D. Hale, S. J. Oldenburg, and N. J. Halas

Appl. Phys. Lett. 71, 1483 (1997); http://dx.doi.org/10.1063/1.119943 (3 pages) | Cited 18 times

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We have used two-photon photoemission as a sensitive monitor of the effects of photo-oxidation on poly[2-methoxy,5-(2′-ethylhexoxy)-1,4-phenylenevinylene] films. We observe a downward shift in the triplet exciton energy as well as a dramatic narrowing of the triplet exciton photoemission linewidth as photo-oxidation progresses. Both of these effects are attributed to changes in the physical and electronic structure of the film due to carbonyl defect formation on the polymer chains. This technique provides a highly sensitive probe of photo-oxidation which may be useful in the optimization of conjugated-polymer-based devices and displays. © 1997 American Institute of Physics.
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79.60.Fr Polymers; organic compounds
61.41.+e Polymers, elastomers, and plastics
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
82.50.-m Photochemistry
68.55.-a Thin film structure and morphology
71.55.Jv Disordered structures; amorphous and glassy solids

Atomic force and scanning electron microscopic observations of surface and domain structures of BaTiO3 films and bulk crystals

S. Tsunekawa, T. Fukuda, T. Ozaki, Y. Yoneda, and H. Terauchi

Appl. Phys. Lett. 71, 1486 (1997); http://dx.doi.org/10.1063/1.119944 (3 pages) | Cited 8 times

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Tapping-mode atomic force and in situ scanning electron microscopic observations of surface and ferroelectric domain structures are performed, respectively, for BaTiO3 crystalline films grown on {100}SrTiO3 substrates by molecular beam epitaxy and for bulk crystals prepared by the top-seeded solution growth technique. Reconstructionlike structures of very long periods are found for the first time in both thin (20 nm) and thick (1000 nm) films. A dependence of the end size of pole-type 180° domains observed in films and bulk crystals on their thickness agrees with the relation expected theoretically. © 1997 American Institute of Physics.
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77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.35.B- Structure of clean surfaces (and surface reconstruction)
77.55.-g Dielectric thin films
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
81.10.Dn Growth from solutions

High resolution transmission electron microscopy study on the microstructures of aluminum nitride and hydrogenated aluminum nitride films prepared by radio frequency reactive sputtering

Yoon-Joong Yong, Jai-Young Lee, Hong Seung Kim, and Jeong Yong Lee

Appl. Phys. Lett. 71, 1489 (1997); http://dx.doi.org/10.1063/1.119945 (3 pages) | Cited 9 times

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Aluminum nitride (AlN) and hydrogenated aluminum nitride (AlN:H) films on Si substrate have been deposited by the radio frequency reactive magnetron sputtering. The microstructures of the two films have been examined and compared by transmission electron microscopy (TEM) and high-resolution TEM. In the growth of the AlN:H film, it has been observed that the amorphous phase is formed at the initial stage of deposition, and c-axis oriented crystallite nucleates at the amorphous layer. The lattice mismatch between the film and substrate and the stress in the film are reduced, and the film surface is smooth due to this amorphous phase. A schematic model explaining the growth of AlN and AlN:H films is proposed, and the reason for the easy formation of the amorphous phase in AlN:H film is discussed.© 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.43.Dq Amorphous semiconductors, metals, and alloys
68.35.B- Structure of clean surfaces (and surface reconstruction)

Formation of buried p-type conducting layers in diamond

R. Walker, S. Prawer, D. N. Jamieson, K. W. Nugent, and R. Kalish

Appl. Phys. Lett. 71, 1492 (1997); http://dx.doi.org/10.1063/1.119946 (3 pages) | Cited 15 times

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Deeply buried boron doped layers are realized in single crystal diamond using MeV ion implantation. Contact to the buried layers is accomplished using pulsed focused laser irradiation which is selectively absorbed in the implanted layer to form a graphite column up to the surface. The contacts are ohmic over a wide range of applied voltage. Implantation induced defects that are responsible for compensation of the acceptors are identified. It is found that removal of these defects requires annealing temperatures of about 1450 °C, but once these defects are removed the buried B doped layer displays excellent activation of the acceptors with an activation energy of 0.372 eV. © 1997 American Institute of Physics.
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61.72.up Other materials
61.80.Jh Ion radiation effects
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
71.55.Cn Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
61.82.Fk Semiconductors

Conformal oxides on Si surfaces

Vincent Tsai, X.-S. Wang, Ellen D. Williams, J. Schneir, and R. Dixson

Appl. Phys. Lett. 71, 1495 (1997); http://dx.doi.org/10.1063/1.119947 (3 pages) | Cited 19 times

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The characteristics of the Si–vacuum interface were compared with the characteristics of the oxide–air interface formed following room temperature oxidation for a variety of samples. Scanning tunneling microscopy was used to measure the surface structure following vacuum preparation, and atomic force microscopy was used to measure the oxide surface on the same samples following exposure to air. Samples investigated included nominally flat Si(111) with equilibrated and quenched surface configurations, Si(111) miscut by 1.25° toward the [211] and equilibrated to yield the faceted structure, and nominally flat Si(001) wafers. In all cases, the step morphology of the clean surfaces was duplicated on the surface of the oxide. © 1997 American Institute of Physics.
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81.05.Cy Elemental semiconductors
81.65.Mq Oxidation
68.35.B- Structure of clean surfaces (and surface reconstruction)

A possible mechanism for improved light-induced degradation in deuterated amorphous-silicon alloy

Jeng-Hua Wei, Ming-Shyan Sun, and Si-Chen Lee

Appl. Phys. Lett. 71, 1498 (1997); http://dx.doi.org/10.1063/1.119972 (3 pages) | Cited 26 times

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We have studied light-induced photoconductivity degradation in an intrinsic hydrogenated and deuterated amorphous-silicon (a-Si) alloy. Deuterated a-Si turns out to be more stable under light exposure. A possible mechanism is proposed to explain this phenomenon. It is attributed to the highly efficient coupling between the localized Si–D wagging modes ( ∼ 510 cm−1) and the extended Si–Si lattice vibration modes ( ∼ 495 cm−1). The energy released from electron or hole capture at silicon dangling bonds causes localized vibrations of nearby Si–D bonds. The energy dissipates quickly to the background lattice and a higher recombination rate at local sites is needed in deuterated a-Si than in hydrogenated amorphous silicon to accumulate enough energy to break the nearby weak bonds. © 1997 American Institute of Physics.
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72.80.Cw Elemental semiconductors
72.80.Ng Disordered solids
72.40.+w Photoconduction and photovoltaic effects
63.20.Pw Localized modes
71.55.Jv Disordered structures; amorphous and glassy solids

Carrier density dependence of the ambipolar diffusion coefficient in GaAs n-i-p structures

D. Streb, G. Klem, W. Fix, P. Kiesel, and G. H. Döhler

Appl. Phys. Lett. 71, 1501 (1997); http://dx.doi.org/10.1063/1.119948 (3 pages) | Cited 3 times

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We report on investigations of the ambipolar diffusion coefficient in GaAs n-i-p structures in which the electron density in the n channel is varied. The ambipolar diffusion coefficient was determined by time-resolved diffusion experiments of the Shockley–Haynes type. The dependence of the ambipolar diffusion coefficient on the varying carrier density is in excellent agreement with the theory of ambipolar diffusion in n-i-p-i systems. In the investigated sample, the ambipolar diffusion coefficient reaches a maximum value of 16 300 cm2/s. Although the ambipolar diffusion constant declines with decreasing carrier density, it is in a wide range of the carrier density more than two orders of magnitude enhanced compared to bulk materials. © 1997 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1−xN films

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner

Appl. Phys. Lett. 71, 1504 (1997); http://dx.doi.org/10.1063/1.119949 (3 pages) | Cited 118 times

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AlxGa1−xN alloys were grown on c-plane sapphire by plasma-induced molecular beam epitaxy. The Al content x was varied over the whole composition range (0 ⩽ x ⩽ 1). The molar Al fraction was deduced from x-ray diffraction and for comparison by elastic recoil detection analysis. The composition of the alloys calculated from the lattice parameter c underestimates x. This is due to a deformation of the unit cell. The exact Al mole fraction and the biaxial strain of the alloys can be calculated by an additional determination of a, using asymmetric reflections. The results obtained by x-ray diffraction and elastic recoil detection provide evidence for the validity of Vegard’s law in the AlGaN system. In addition, the deviation of the band gap from a linear dependence on x was investigated. We found a downward bowing with a bowing parameter b = 1.3 eV.© 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
73.61.Ey III-V semiconductors
68.60.Bs Mechanical and acoustical properties
68.55.Nq Composition and phase identification
61.66.Bi Elemental solids
61.66.Dk Alloys
71.20.Nr Semiconductor compounds

Characterization of wafer bonded photodetectors fabricated using various annealing temperatures and ambients

B. F. Levine, A. R. Hawkins, S. Hiu, B. J. Tseng, J. P. Reilley, C. A. King, L. A. Gruezke, R. W. Johnson, D. R. Zolnowski, and J. E. Bowers

Appl. Phys. Lett. 71, 1507 (1997); http://dx.doi.org/10.1063/1.119950 (3 pages) | Cited 8 times

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A detailed study of the important role of temperature and gas ambient on the bonding between Si and InGaAs wafers was performed. The heterointerface was characterized by fabricating p-i-n photodetectors and measuring the forward and reverse currents, the capacitance, the absolute quantum efficiency, and the response bandwidth. Clear evidence for a thin tunneling barrier is found for nonoptimum fusing conditions. © 1997 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
61.72.Cc Kinetics of defect formation and annealing

CdSe/ZnSe quantum structures grown by migration enhanced epitaxy: Structural and optical investigations

K. Leonardi, H. Heinke, K. Ohkawa, D. Hommel, H. Selke, F. Gindele, and U. Woggon

Appl. Phys. Lett. 71, 1510 (1997); http://dx.doi.org/10.1063/1.119951 (3 pages) | Cited 53 times

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Migration enhanced epitaxy has been applied to induce the change from two-dimensional growth to formation of self-assembling islands in the growth of CdSe on ZnSe. Transmission electron microscopy images from samples with a ZnSe caplayer show a transition from a flat quantum well to an interrupted layer with pronounced thickness fluctuations when the CdSe exceeds its critical thickness. These results are confirmed by high resolution x-ray diffraction measurements, as only for the former sample the 004 rocking curve can be simulated assuming a flat quantum well with abrupt interfaces. Compared to bulk CdSe, the photoluminescence peak is blueshifted by about 0.5 eV. PL excitation experiments indicate that the interrupted layer consists of CdSe islands embedded in Zn1−xCdxSe with a composition gradient. Atomic force microscopy images of uncapped samples show spherical islands with a height of 20 nm and a diameter-to-height ratio of 4:1. © 1997 American Institute of Physics.
Show PACS
81.05.Dz II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.66.Hf II-VI semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Et II-VI semiconductors
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