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3 Jun 1991

Volume 58, Issue 22, pp. 2459-2567

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Cross‐linked stable second‐order nonlinear optical polymer by photochemical reaction

Braja K. Mandal, Yong M. Chen, Jun Y. Lee, Jayant Kumar, and Sukant Tripathy

Appl. Phys. Lett. 58, 2459 (1991); http://dx.doi.org/10.1063/1.104843 (2 pages) | Cited 54 times

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A new method for obtaining cross‐linked second‐order nonlinear optical polymer by photochemical reaction has been described. An active dye was processed and poled in a photoreactive polymer in a manner similar to doped polymer system, and photo‐cross‐linked in the poled phase by ultraviolet irradiation. The dye doped (20% by weight) cross‐linked polymer has a nonlinear optical coefficient d33 of 5.1 pm/V at 1.540 μm and shows no relaxation after being subjected to thermal treatment at 60 °C for 0.5 h.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.-a Optical materials
78.20.Jq Electro-optical effects
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light

Observation of plasmon‐enhanced optical extinction in silver‐coated silver bromide nanoparticles

Jovan Nedeljkovic and Ramesh C. Patel

Appl. Phys. Lett. 58, 2461 (1991); http://dx.doi.org/10.1063/1.104844 (3 pages) | Cited 3 times

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Silver bromide nanoparticles exposed briefly to intense UV light in the presence of ethylenediaminetetraacetic acid (EDTA) have optical extinction spectra similar to those computed for distributions of silver‐coated silver bromide nanoparticles. With longer exposure times the plasmon resonance maximum is shifted to shorter wavelengths, a result consistent with theory so long as the coat thickness increases with exposure to light. The resonance maximum of the distribution of coated particles can be controllably shifted from 400 up to 700 nm.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

High‐power, very low threshold, GaInP/AlGaInP visible diode lasers

H. B. Serreze, Y. C. Chen, and R. G. Waters

Appl. Phys. Lett. 58, 2464 (1991); http://dx.doi.org/10.1063/1.104845 (3 pages) | Cited 17 times

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Visible light (665 nm) laser diodes employing a strained‐layer, single quantum well, graded index separate confinement heterostructure were fabricated from epitaxial wafers grown by metalorganic chemical vapor deposition. Threshold current densities for single element, uncoated, broad‐area diodes operated cw as low as 425 A/cm2, cw power outputs of 340 mW per facet, and pulsed outputs (100 μs pulse width) of slightly under 1 W per facet were achieved. These power output values are believed to be the highest reported to date for visible light diode lasers, and this cw threshold current density is believed to be, by far, the lowest.
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42.55.Px Semiconductor lasers; laser diodes
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.45.+h Stimulated emission
85.60.Jb Light-emitting devices

Quantum well infrared photodetectors: Monte Carlo simulations of transport

M. Artaki and I. C. Kizilyalli

Appl. Phys. Lett. 58, 2467 (1991); http://dx.doi.org/10.1063/1.104846 (3 pages) | Cited 2 times

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This letter describes some Monte Carlo simulations of electron transport in quantum well infrared photodetectors designed to operate in the 10 μm wavelength range. These GaAs/AlGaAs superlattice photodetectors absorb radiation between a bound state in the wells and the continuum of states above the wells. We have studied the collection efficiency of the photoexcited electrons at 70 K as a function of bias across the device, as well as the response time. It is concluded that the quantum mechanical well capture transition rate through interaction with LO phonons, between the extended states in the continuum and the bound state, has to be considered for agreement with the experimental results.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.De Semiconductor-device characterization, design, and modeling
42.50.-p Quantum optics

Femtosecond passive mode locking of a solid‐state laser by a dispersively balanced nonlinear interferometer

Ch. Spielmann, F. Krausz, T. Brabec, E. Wintner, and A. J. Schmidt

Appl. Phys. Lett. 58, 2470 (1991); http://dx.doi.org/10.1063/1.104847 (3 pages) | Cited 12 times

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A Michelson interferometer containing a nonlinear fiber in one arm and dispersion control in the other arm has been used for passive mode locking of a continuous wave Nd:glass laser. We discuss scaling issues and demonstrate the usefulness of this technique by generating ≊300 fs pulses with only Pf≊15 mW of average power in the fiber and ≊100 fs pulses with a self‐starting threshold of Pf≊100 mW.  
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42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers
07.60.Ly Interferometers
42.15.Eq Optical system design

Neutral gas temperatures in a multipolar electron cyclotron resonance plasma

J. Hopwood and J. Asmussen

Appl. Phys. Lett. 58, 2473 (1991); http://dx.doi.org/10.1063/1.105232 (3 pages) | Cited 20 times

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Optical emission measurements of the Doppler broadening of argon (549.6 nm) and helium (501.6 nm) neutral lines in the unmagnetized regions of an electron cyclotron resonance plasma show that the gas temperature ranges from 300 to 900 K. After compensation for Zeeman splitting, Doppler widths are found to be constant across the radius of the plasma. Plasma heating of the argon gas (0.77 mTorr) is shown to increase from 300 to 500 K as microwave power absorption increases from 80 to 330 W. Long neutral residence times are observed to increase the argon gas temperature to ≊900 K. Helium and argon neutral temperatures decrease as the neutral mean free path increases indicating that the gas may be heated by ion‐neutral collisions including charge exchange.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Deposition of composition‐controlled silicon oxynitride films by dual ion beam sputtering

S. K. Ray, S. Das, C. K. Maiti, S. K. Lahiri, and N. B. Chakrabarti

Appl. Phys. Lett. 58, 2476 (1991); http://dx.doi.org/10.1063/1.104848 (3 pages) | Cited 2 times

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Silicon oxynitride films of controlled composition have been deposited on silicon by dual ion beam sputtering (DIBS) making simultaneous use of an energetic argon ion beam to sputter silicon nitride from a target and a low‐energy oxygen ion beam to react with the sputtered film on the substrate. The correspondence between film properties and oxygen beam parameters has been studied from measurements of refractive index, chemical etch rate, infrared absorption, and x‐ray photoelectron spectroscopy spectra. In situ ion beam oxidation of silicon prior to oxynitride deposition results in a film with a low insulator charge density (3.5×1011 cm−2) and interface trap density (4×1011 cm−2 eV−1).
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81.15.Cd Deposition by sputtering
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.61.Ng Insulators
85.40.Hp Lithography, masks and pattern transfer

Pulsed laser deposition of stoichiometric potassium‐tantalate‐niobate films from segmented evaporation targets

S. Yilmaz, T. Venkatesan, and R. Gerhard‐Multhaupt

Appl. Phys. Lett. 58, 2479 (1991); http://dx.doi.org/10.1063/1.104849 (3 pages) | Cited 41 times

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The preparation of epitaxial potassium‐tantalate‐niobate (KTa0.7Nb0.3O3, KTN) films on strontium‐titanate substrates by means of pulsed excimer laser evaporation in vacuum is reported. In the most successful deposition experiments, a segmented evaporation target consisting of a semicircular KTN single crystal and a semicircular potassium nitrate pellet was utilized−to our knowledge for the first time; it was thus possible to overcome the otherwise observed partial loss of the volatile potassium and to avoid potassium deficiency in the KTN films. Rutherford backscattering spectrometry and x ray diffraction results indicate that the samples have the desired stoichiometric composition as well as the orientation prescribed by the substrate crystal.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.10.Bk Growth from vapor
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
78.20.Jq Electro-optical effects

Growth of cubic boron nitride on diamond particles by microwave plasma enhanced chemical vapor deposition

H. Saitoh and W. A. Yarbrough

Appl. Phys. Lett. 58, 2482 (1991); http://dx.doi.org/10.1063/1.104850 (3 pages) | Cited 34 times

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The nucleation and growth of cubic boron nitride (c‐BN) onto diamond powder using solid NaBH4 in low pressure gas mixtures of NH3 and H2 by microwave plasma enhanced chemical vapor deposition has been studied. Boron nitride was deposited on submicron diamond seed crystals scattered on (100) silicon single crystal wafers and evidence was found for the formation of the cubic phase. Diamond powder surfaces appear to preferentially nucleate c‐BN. In addition it was found that the ratio of c‐BN to turbostratic structure boron nitride (t‐BN) deposited increases with decreasing NH3 concentration in H2. It is suggested that this may be due to an increased etching rate for t‐BN by atomic hydrogen whose partial pressure may vary with NH3 concentration.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
64.60.Q- Nucleation
82.60.Nh Thermodynamics of nucleation

Large‐area mosaic diamond films approaching single‐crystal quality

M. W. Geis, Henry I. Smith, A. Argoitia, J. Angus, G.‐H. M. Ma, J. T. Glass, J. Butler, C. J. Robinson, and R. Pryor

Appl. Phys. Lett. 58, 2485 (1991); http://dx.doi.org/10.1063/1.104851 (3 pages) | Cited 34 times

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The seeding for large‐area mosaic diamond films approaching single‐crystal quality is described. The technique includes patterned etching of relief structures in Si substrates, deposition from a slurry and orientation of macroscopic diamond seed crystals in the structures, and chemical vapor deposition overgrowth of the diamond seeds to form a continuous film. The film comprises ∼100 μm single crystals, which are separated by low‐angle grain boundaries of a few degrees or less. We believe that these low‐angle grain boundaries will not affect the electrical properties of majority‐carrier devices.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.61.Ng Insulators
61.43.Fs Glasses
61.43.-j Disordered solids
61.44.Br Quasicrystals

Residual stress at fluid interfaces with application to silicon oxidation

Paul E. Murray

Appl. Phys. Lett. 58, 2488 (1991); http://dx.doi.org/10.1063/1.104852 (3 pages) | Cited 2 times

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A fluid may undergo a constrained volume change as a result of the presence of a soluble chemical species. Corresponding to every constrained volume change is a residual stress. We present a method to include in the equations of fluid motion a body force to allow for the presence of residual stress. This method is used to calculate the residual stress associated with the chemical transformation of silicon to silicon dioxide in the presence of water vapor.
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68.08.-p Liquid-solid interfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
85.30.De Semiconductor-device characterization, design, and modeling
81.65.-b Surface treatments

Electrically tunable and polarization insensitive Fabry–Perot étalon with a liquid‐crystal film

J. S. Patel and Sin‐Doo Lee

Appl. Phys. Lett. 58, 2491 (1991); http://dx.doi.org/10.1063/1.104853 (3 pages) | Cited 33 times

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A polarization insensitive, electrically tunable Fabry–Perot structure is demonstrated. The polarization insensitivity is realized by using a twisted structure of a nematic liquid crystal such that the molecules at one surface are orthogonal to those at the other surface. In the high‐field regime, this configuration can be thought of as a structure composed of two orthogonal, birefringent slabs with the electrically controllable thickness. At low voltages the device is polarization sensitive but becomes polarization insensitive at relatively higher voltages. In the polarization insensitive region, the linewidth of the transmission peak is of the order of 0.5 nm and the tuning range is about 15 nm.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
07.60.Ly Interferometers
78.20.Fm Birefringence
78.20.Jq Electro-optical effects

Preparation of stable and photoconductive hydrogenated amorphous silicon from a Xe‐diluted silane plasma

A. Matsuda, S. Mashima, K. Hasezaki, A. Suzuki, S. Yamasaki, and P. J. McElheny

Appl. Phys. Lett. 58, 2494 (1991); http://dx.doi.org/10.1063/1.104854 (3 pages) | Cited 16 times

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Photoconductive and stable hydrogenated amorphous silicon thin films, prepared by plasma‐enhanced chemical vapor deposition using a Xe‐silane mixture at a substrate temperature of 250 °C, did not show any photo‐induced degradation of the photoconductivity after 104 min light soaking (air mass‐1, 100 mW/cm2). The network structure of these films is inhomogeneous and includes a large amount of clustered hydrogen as indicated by the low‐temperature thermal effusion and the large, broad component in the nuclear magnetic resonance spectrum.
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73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology

In situ stress measurements of ion‐assisted MgF2 and SiOx thin films

P. J. Martin, R. P. Netterfield, T. J. Kinder, and V. Stambouli

Appl. Phys. Lett. 58, 2497 (1991); http://dx.doi.org/10.1063/1.104855 (3 pages) | Cited 1 time

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An in situ stress measuring interferometer and in situ ellipsometer have been used to study the stress evolution and optical properties of MgF2 and SiOx optical thin films prepared by electron beam evaporation and 100 eV O+2 ion‐assisted deposition (IAD). The maximum stress observed in thermal evaporation of MgF2 was found to be 240 MPa. The tensile stress in evaporated MgF2 could be modified by IAD to compressive stress. The optical properties and stress of SiOx were modified by IAD and also by the presence of a partial pressure of oxygen. The combination of stress interferometry and ellipsometry is shown to be a powerful method of monitoring and controlling the properties of optical materials deposited by IAD.
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78.66.-w Optical properties of specific thin films
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
68.35.Gy Mechanical properties; surface strains

Variations of resonant tunneling properties with temperature in strained Si1−xGex/Si double‐barrier structures

D. X. Xu, G. D. Shen, M. Willander, G. V. Hansson, J. F. Luy, and F. Schäffler

Appl. Phys. Lett. 58, 2500 (1991); http://dx.doi.org/10.1063/1.104856 (3 pages) | Cited 7 times

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We have investigated the resonant tunneling feature variations with temperature in molecular beam epitaxy grown strained Si0.78Ge0.22/Si double‐barrier structures with different well width w and spacer thickness LS. Both w and LS have strong effects on the temperature characteristics of the peak current JP, the valley current JV, and the current peak‐to‐valley ratio (PVR). When w is reduced, both JP and JV are greatly increased. The resonant tunneling devices (RTDs) also have better temperature stability and PVR decreases slower. The RTD with larger LS has higher peak current. Beside w and LS, the quasi‐Fermi level position has a very important influence on the resonant tunneling feature variations, which is stressed in the present work.
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73.40.Gk Tunneling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Transit time limited response of GaAs metal‐semiconductor‐metal photodiodes

M. Klingenstein, J. Kuhl, J. Rosenzweig, C. Moglestue, and A. Axmann

Appl. Phys. Lett. 58, 2503 (1991); http://dx.doi.org/10.1063/1.104857 (3 pages) | Cited 20 times

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The response of GaAs metal‐semiconductor‐metal (MSM) photodiodes at low temperatures has been investigated in the time domain by photoconductive sampling. The dependence of the response time on temperature for T≳50 K can be described by phonon mediated intervalley and intravalley scattering. The pulse width drops from 10.8 ps at 300 K to 5.6 ps at 70 K and then grows rapidly with decreasing temperature below 50 K. These results demonstrate that the response is limited by the electron/hole transport in the semiconductor rather than by external capacitances or inductances.
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85.60.Dw Photodiodes; phototransistors; photoresistors
78.47.-p Spectroscopy of solid state dynamics
84.40.Az Waveguides, transmission lines, striplines
85.30.De Semiconductor-device characterization, design, and modeling

Precise measurements of oxygen content: Oxygen vacancies in transparent conducting indium oxide films

J. R. Bellingham, A. P. Mackenzie, and W. A. Phillips

Appl. Phys. Lett. 58, 2506 (1991); http://dx.doi.org/10.1063/1.104858 (3 pages) | Cited 43 times

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High precision electron probe microanalysis (EPMA) has been used to measure the correlation of oxygen deficiency with carrier concentration in thin films of amorphous indium oxide. This has shown that there are ten times as many oxygen vacancies as would be expected from the carrier concentration measurements, giving a doping efficiency of 0.1. It is therefore clear that the doping mechanism is more complex than the usual picture of every oxygen vacancy producing two free electrons.
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73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
81.15.Cd Deposition by sputtering
61.72.jd Vacancies
61.72.jj Interstitials
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Evolution of the band gap and the dominant radiative recombination center versus the composition for ZnSe1−xTex alloys grown by molecular beam epitaxy

M. J. S. P. Brasil, R. E. Nahory, F. S. Turco‐Sandroff, H. L. Gilchrist, and R. J. Martin

Appl. Phys. Lett. 58, 2509 (1991); http://dx.doi.org/10.1063/1.104859 (3 pages) | Cited 43 times

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We report a systematic study of the optoelectronic properties of ZnSe1−xTex alloys grown by molecular beam epitaxy over the entire range of compositions. The band‐gap energy as a function of the composition presents a minimum at x≂0.65. The main luminescence emission observed at 5 K becomes narrower and closer to the band‐gap energy as we increase the Te content. The linewidth and the difference between the emission peak and band‐gap energy decrease significantly with increasing x and present a break in the slope at x≂0.65.
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78.55.Et II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
71.55.Gs II-VI semiconductors

Modulated electric conductivity in Fe3O4/NiO superlattices

G. Chern, S. D. Berry, D. M. Lind, H. Mathias, and L. R. Testardi

Appl. Phys. Lett. 58, 2512 (1991); http://dx.doi.org/10.1063/1.104860 (2 pages) | Cited 7 times

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High quality Fe3O4/NiO multilayered structures with nominal artificial periodicity 17 Å/ 17 Å and 34 Å/34 Å have been made by molecular beam epitaxy. The conductivity of the modulated structures is orders of magnitude higher for current parallel to the layers than for the transverse direction, reaching a ratio of 106−a value which is comparable with the largest known anisotropy for any material. This strong anisotropy shows that a like modulation of electrical conductivity has been achieved over distances as small as tens of Å and also suggests the possibility of voltage controlled superlattice phenomena.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.50.Fq High-field and nonlinear effects
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

AlxGa1−xAs/GaAs photovoltaic cell with epitaxial isolation layer

G. Subramanian, A. Dodabalapur, J. C. Campbell, and B. G. Streetman

Appl. Phys. Lett. 58, 2514 (1991); http://dx.doi.org/10.1063/1.104861 (3 pages) | Cited 1 time

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Efficient integration of multijunction photovoltaic cells requires current matching or voltage matching. To match voltages it is necessary to achieve complete electrical isolation between the component cells. Previously, electrical isolation could only be achieved with hybrid, mechanically stacked structures. We report the growth, fabrication, and characterization of an AlxGa1−xAs/GaAs photovoltaic cell with an epitaxial isolation layer of semi‐insulating GaAs grown by molecular beam epitaxy. This will facilitate the integration of subcells that absorb different portions of the solar spectrum onto a single substrate.
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73.50.Pz Photoconduction and photovoltaic effects
85.60.-q Optoelectronic devices
84.60.Jt Photoelectric conversion

Influence of trench depth on the misfit dislocation density at strained epitaxial layer interfaces grown on patterned GaAs substrates

G. Patrick Watson, Dieter G. Ast, Timothy J. Anderson, and Yasuhiro Hayakawa

Appl. Phys. Lett. 58, 2517 (1991); http://dx.doi.org/10.1063/1.104862 (3 pages) | Cited 4 times

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The number of misfit dislocations in strained, epitaxial InGaAs layers can be significantly reduced by growing on patterned substrates. Etched trenches on these substrates block misfit dislocation propagation from mesa to mesa. To determine the minimum trench depth needed to block misfit dislocations, 200 μm×200 μm mesas separated by 10‐μm‐wide trenches of varying depths were etched into a GaAs substrate before organometallic chemical vapor deposition of 300 or 600 nm In0.04Ga0.96As strained layers (several times the critical thickness). Three isolation regimes are seen in the 300‐nm‐thick InGaAs samples. The shallowest trenches, regime I, below 300 nm, do not completely block all dislocations. Misfit dislocations are blocked by trenches 300–500 nm deep, regime II, after they glide down the mesa walls and stop at the far side of the trenches. Trenches greater than 500 nm, regime III, stop dislocations at the mesa edges. The 600‐nm‐thick InGaAs layers with trench depths greater than 450 nm completely stopped all misfit dislocations. The third regime did not occur for trenches as deep as 650 nm. These results show that the epitaxial layer does not have to be discontinuous to prevent misfit dislocations from gliding across patterned substrates.
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68.55.-a Thin film structure and morphology
68.35.Fx Diffusion; interface formation
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)

Influence of trap filling on photocurrent transients in polycrystalline TiO2

K. Schwarzburg and F. Willig

Appl. Phys. Lett. 58, 2520 (1991); http://dx.doi.org/10.1063/1.104839 (3 pages) | Cited 71 times

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Electron injection from optically excited dye molecules into the depletion layer of polycrystalline n‐TiO2 electrodes is measured as photocurrent. The characteristic shape of the photocurrent transients has a point of inflection and is controlled by the complete filling of deep traps. The rate equations for the Shockley–Read trapping process are solved numerically for the case of high injection levels, and the shape of the transients is simulated.
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73.50.Pz Photoconduction and photovoltaic effects
73.50.Fq High-field and nonlinear effects
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ng Insulators

Interface roughness limited electron mobility in HgTe‐CdTe superlattices

J. R. Meyer, D. J. Arnold, C. A. Hoffman, and F. J. Bartoli

Appl. Phys. Lett. 58, 2523 (1991); http://dx.doi.org/10.1063/1.104840 (3 pages) | Cited 22 times

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We demonstrate that interface roughness is the dominant low‐temperature scattering mechanism for electrons in HgTe‐CdTe superlattices with thin wells. Not only do the experimental mobilities follow the expected d6W dependence, but the observed temperature dependence is accurately reproduced by theory when the treatment of interface roughness scattering is generalized for narrow‐gap superlattices. The fits to data yield roughness correlation lengths in the range 60–200 Å.
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73.61.Ga II-VI semiconductors
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.50.Dn Low-field transport and mobility; piezoresistance

Sub‐30 nm lithography in a negative electron beam resist with a vacuum scanning tunneling microscope

E. A. Dobisz and C. R. K. Marrian

Appl. Phys. Lett. 58, 2526 (1991); http://dx.doi.org/10.1063/1.104841 (3 pages) | Cited 35 times

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We report studies of minimum feature sizes in 50 nm films of the high‐resolution negative electron beam resist, SAL‐601‐ER7 from the Shipley Corporation. Developed linewidths of 27 nm and line spacing of 55 nm, from center to center, were produced by lithography with a vacuum scanning tunneling microscope (STM). In contrast, a minimum linewidth of 95 nm was obtained from exposure with a 17 nm (1/e diameter) 50 kV electron beam. Patterns written in the STM at electron energies down to 15 eV were visible in the developed resist. The limit at 15 eV is related to the operation of the STM and does not represent an exposure threshold energy for the resist.
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85.40.Hp Lithography, masks and pattern transfer
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
81.05.Kf Glasses (including metallic glasses)
81.65.-b Surface treatments

Effect of melt‐growth processing methods on Si‐Ge‐GaP homogeneity

R. J. Kilmer, W. A. Jesser, and F. D. Rosi

Appl. Phys. Lett. 58, 2529 (1991); http://dx.doi.org/10.1063/1.104842 (3 pages) | Cited 1 time

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Three processing methods were employed to homogenize a Si0.80Ge0.20 alloy hot pressed with additions of approximately 2 a/o GaP. The melt‐growth methods investigated include single‐pass zero melting, zone leveling, and splat cooling. Energy dispersive spectroscopy was performed in conjunction with scanning electron microscopy and transmission electron microscopy along with x‐ray diffractometer analysis to characterize the resultant ingots. The single‐pass zone‐melted ingot exhibited a higher GaP content than the zone‐leveled ingot probably as a consequence of a higher growth temperature during zone melting. Both ingots had large regions of uniform average composition whereas the splat cooled alloy exhibited a marked inhomogeneity.
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81.10.Fq Growth from melts; zone melting and refining
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
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