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24 Sep 1990

Volume 57, Issue 13, pp. 1283-1365

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Reducing slip in a far‐infrared free‐electron laser using a parallel‐plane waveguide

S. K. Ride, R. H. Pantell, and J. Feinstein

Appl. Phys. Lett. 57, 1283 (1990); http://dx.doi.org/10.1063/1.103460 (3 pages) | Cited 9 times

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There are several interesting applications for a picosecond, far‐infrared (100–1000 μ) free‐electron laser. One obstacle to its development is the slip that occurs between the electron beam and the radiation. This can be reduced by operating the laser in a parallel‐plane waveguide, and choosing the laser parameters and transverse guide dimension such that the group velocity of the wave nearly matches the axial velocity of the electrons. The laser wavelength depends on both the electron energy and the waveguide dimension, and the laser can be tuned by varying either. Both the tuning characteristics and the slip as a function of wavelength are different from those of a conventional free‐electron laser.
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41.60.Cr Free-electron lasers
52.59.Px Hard X-ray sources
41.75.Ht Relativistic electron and positron beams

Optical waveguide microscopy

Werner Hickel and Wolfgang Knoll

Appl. Phys. Lett. 57, 1286 (1990); http://dx.doi.org/10.1063/1.103461 (3 pages) | Cited 18 times

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Optical waveguide microscopy is introduced as a novel imaging technique that allows for the microscopic characterization of thin‐film samples by using guided optical waves as illumination light source. Excellent thickness (<1 nm) and good lateral resolution (<10 μm) is demonstrated. As a first application we image and analyze the two‐dimensional thickness profile of a planar polymeric spun‐on waveguide structure.
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07.60.Pb Conventional optical microscopes
78.66.-w Optical properties of specific thin films
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
68.60.-p Physical properties of thin films, nonelectronic

Low‐threshold surface‐emitting laser diodes with distributed Bragg reflectors and current blocking layers

M. Shimada, T. Asaka, Y. Yamasaki, H. Iwano, M. Ogura, and S. Mukai

Appl. Phys. Lett. 57, 1289 (1990); http://dx.doi.org/10.1063/1.104096 (3 pages) | Cited 4 times

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AlGaAs/GaAs surface‐emitting laser diodes (SELDs) with distributed Bragg reflectors (DBRs) and current blocking layers are fabricated with the combination of a two‐step epitaxial growth and the reactive ion beam etching (RIBE) technique. An Al0.1Ga0.9As/Al0.7Ga0.3As multilayer and an amorphous silicon (a‐Si)/silicon dioxide (SiO2) multilayer are employed for the lower and upper mirrors, respectively. The active region has a 5×5 μm or 4 μm ϕ area and a 0.8 μm thickness. The minimum threshold current is 3.3 mA under pulsed condition and 4.1 mA under continuous wave (cw) operation at 12 °C with junction‐side‐up configuration. Stable single longitudinal mode is observed, and far‐field pattern (FFP) indicates higher transverse mode operation.
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42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Efficient GaInAsSb/AlGaAsSb diode lasers emitting at 2.29 μm

S. J. Eglash and H. K. Choi

Appl. Phys. Lett. 57, 1292 (1990); http://dx.doi.org/10.1063/1.103462 (3 pages) | Cited 30 times

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Diode lasers emitting at 2.29 μm have been fabricated from lattice‐matched double heterostructures having a GaInAsSb active layer and AlGaAsSb confining layers grown by molecular beam epitaxy on GaSb substrates. For pulsed room‐temperature operation these devices have exhibited threshold current densities as low as 1.7 kA/cm2 and differential quantum efficiencies as high as 18% per facet, the highest room‐temperature efficiency reported for any semiconductor diode laser emitting beyond 2 μm.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

InGaAs/InP distributed feedback quantum well laser

H. Temkin, T. Tanbun‐Ek, R. A. Logan, N. A. Olsson, M. A. Sergent, K. W. Wecht, and D. A. Cebula

Appl. Phys. Lett. 57, 1295 (1990); http://dx.doi.org/10.1063/1.103463 (3 pages) | Cited 4 times

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We describe InGaAs/InP multiquantum well distributed feedback (DFB) lasers with novel properties atrributable to the quantum well based active layer. The low internal loss waveguide and shallow gratings have allowed the fabrication of lasers with a cavity length varying from 0.5 to 2 mm, and corresponding threshold currents of 22 and 100 mA, respectively. A mode rejection ratio as high as 50 dB has been obtained in lasers with one antireflection‐coated facet. The long cavity devices exhibit linewidths as low as 600 kHz at a power output of 35 mW. Transmission experiments through 70 km of fiber, at 1.7 Gb/s, showed a dynamic chirp penalty of only 0.25 dB, a factor of 8–10 smaller than in conventional lasers.
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42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking

High‐reflectivity self‐pumped phase conjugator using total internal reflection in KNbNO3:Fe

He‐Yi Zhang, Xue Hua He, Erli Chen, Yue Liu, Sing Hai Tang, De‐Zheng Shen, and Da‐Ya Jiang

Appl. Phys. Lett. 57, 1298 (1990); http://dx.doi.org/10.1063/1.103464 (3 pages) | Cited 13 times

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A self‐pumped phase conjugate reflectivity of 74.8% is obtained with a suitably cut KNbO3:Fe crystal in a polygonal shape. The design and operation of this self‐pumped phase conjugator is described. The build‐up time is observed to be dependent on the input power. The phase conjugate nature of the retroreflected beam has been further confirmed by a significant decrease in the specular reflectivity of the input surface of the crystal.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.-a Optical materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Femtosecond‐response, highly third‐order nonlinear 4‐(N, N‐dimethylamino)‐3‐acetamidonitrobenzene crystal cored fiber

Mikio Yamashita, Kenji Torizuka, and Takafumi Uemiya

Appl. Phys. Lett. 57, 1301 (1990); http://dx.doi.org/10.1063/1.103465 (3 pages) | Cited 6 times

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A nonlinear refractive index n2.DAN of a 4‐(N, N‐dimethylamino)‐3‐acetamidonitrobenzene (DAN) single‐crystal cored fiber of 3.9 mm length and 2.3 μm core radius is evaluated by observing the spectral broadening of a 250 fs pulse due to dispersive self‐phase modulation in its fiber and that in a conventional fused‐silica fiber. The result shows that the value of the femtosecond‐response n2.DAN in the nonabsorbing wavelength region around 625 nm is 1.7×104 times as large as that of the latter’s glass fiber.
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42.70.-a Optical materials
42.81.Gs Birefringence, polarization
78.20.-e Optical properties of bulk materials and thin films

Novel method for determining the electromagnetic dispersion relation of periodic slow wave structures

Y. Carmel, H. Guo, W. R. Lou, D. Abe, V. L. Granatstein, and W. W. Destler

Appl. Phys. Lett. 57, 1304 (1990); http://dx.doi.org/10.1063/1.103466 (3 pages) | Cited 9 times

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A novel method for calculating the dispersion relation of electromagnetic modes in an arbitrary periodic slow wave structure is reported. In this method it is sufficient to know the frequencies corresponding to three special wave number values, with other points calculated using an approximate analytical expression. This technique was successfully applied to determine the dispersion relation of the TM01 mode in a sinusoidally corrugated slow wave structure. This structure is commonly used in relativistic high‐power backward wave oscillators and traveling‐wave tubes, and is expected to have many additional applications.
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84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)
52.59.Px Hard X-ray sources
52.27.Ny Relativistic plasmas
52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)

Interaction of Cu with CoSi2 with and without TiNx barrier layers

J. O. Olowolafe, Jian Li, B. Blanpain, and J. W. Mayer

Appl. Phys. Lett. 57, 1307 (1990); http://dx.doi.org/10.1063/1.104230 (3 pages) | Cited 8 times

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Thermally induced interactions of Cu with CoSi2, with and without interposed TiNx layers, have been studied using Rutherford backscattering spectrometry, Auger electron spectroscopy, and x‐ray diffraction. Cu diffuses through a preformed CoSi2 layer to form the structure Cu/CoSi2/Cu3Si/Si at temperatures above 300 °C, and no dissociation of CoSi2 occurs. A 50 nm TiNx(x≊1) layer is observed to be an effective diffusion barrier up to about 500 °C between Cu and CoSi2.
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68.35.Fx Diffusion; interface formation
85.40.Hp Lithography, masks and pattern transfer
66.30.J- Diffusion of impurities

Threshold reduction through photon recycling in semiconductor lasers

Yves B. Gigase, Christoph S. Harder, Morris P. Kesler, Heinz P. Meier, and Bart Van Zeghbroeck

Appl. Phys. Lett. 57, 1310 (1990); http://dx.doi.org/10.1063/1.103467 (3 pages) | Cited 3 times

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The threshold pump power of an AlGaAs‐GaAs ridge quantum well laser diode has been reduced by 42% by recycling the spontaneous emission. An integrated photodiode absorbs the spontaneous radiation emitted by the laser diode and converts it back into electrical power. The recycling of this power results in a reduction of the electrical power required to reach the lasing threshold.
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42.60.By Design of specific laser systems
78.45.+h Stimulated emission
85.60.Jb Light-emitting devices

Observation of domain boundaries on the Si (111) 7×7 surface by scanning tunneling microscope

I. Sumita, T. Yokotsuka, H. Tanaka, M. Udagawa, Y. Watanabe, M. Takao, and K. Yokoyama

Appl. Phys. Lett. 57, 1313 (1990); http://dx.doi.org/10.1063/1.103468 (3 pages) | Cited 7 times

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A highly reliable scanning tunneling microscope system equipped with a field ion microscope yielded successful observation of a domain boundary on the Si(111) 7×7 reconstructed surface. For the first time, we revealed its detailed structure at the atomic level. The boundary consists of holes far larger than the corner holes of the dimer‐adatom‐stacking fault (DAS) model and bridge‐like structures with three 2×2 subunits. The ditch structure of this boundary is running to the [110] direction, i.e., to the direction of the shorter diagonal of the 7×7 unit cell. We discussed that a misfit of the 7×7 periodicity between the neighboring domains caused this ditch structure.
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68.35.Dv Composition, segregation; defects and impurities
68.35.B- Structure of clean surfaces (and surface reconstruction)
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
73.40.Gk Tunneling

Electronic properties of a pulse‐doped GaAs structure grown by organometallic vapor phase epitaxy

Shigeru Nakajima, Nobuhiro Kuwata, Naoki Nishiyama, Nobuo Shiga, and Hideki Hayashi

Appl. Phys. Lett. 57, 1316 (1990); http://dx.doi.org/10.1063/1.103469 (2 pages) | Cited 6 times

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A pulse‐doped GaAs structure was grown by organometallic vapor phase epitaxy using a conventional doping technique. Existence of a two‐dimensional electron gas confined in this structure was confirmed by Schubnikov–de Haas measurement. Electron mobility and concentration are evaluated by Hall measurement. Electron mobility and concentration dependence on temperature of a pulse‐doped GaAs are similar to those of a δ‐doped GaAs.
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71.55.Eq III-V semiconductors
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
73.61.Ey III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Deep Ti donor in GaAs

H. Scheffler, W. Korb, D. Bimberg, and W. Ulrici

Appl. Phys. Lett. 57, 1318 (1990); http://dx.doi.org/10.1063/1.103470 (3 pages) | Cited 9 times

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Ti‐doped GaAs crystals grown by the liquid‐encapsulated Czochralski method were investigated by using the observation of direct capacitance transients. The charge transfer transitions to the deep Ti donor level close to midgap are unambiguously identified in both n‐type and p‐type material. The energy position of Ti3+/Ti4+ is determined with high precision of Ec−(0.87±0.01) eV at 300 K and the respective cross sections are σn∞=(7±3)×10−15 cm2 for electron capture and σp∞=(10±5)×10−16 cm2 for hole capture. The position of the Ti2+/Ti3+ acceptor is confirmed to be at Ec−(0.19±0.01) eV. Its cross section for electron capture is σn∞=(3±1)×10−16 cm2.
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71.55.Eq III-V semiconductors
72.80.Ga Transition-metal compounds
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Characterization of DX centers in selectively doped GaAs‐AlAs superlattices

S. Ababou, J. J. Marchand, L. Mayet, G. Guillot, and F. Mollot

Appl. Phys. Lett. 57, 1321 (1990); http://dx.doi.org/10.1063/1.103471 (3 pages) | Cited 4 times

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Using deep level transient spectroscopy (DLTS), DX center has been characterized in GaAs‐AlAs superlattices grown by molecular beam epitaxy and selectively Si‐doped either in the AlAs layers or in the middle of the GaAs layers. The activation energy for thermal emission, which is the summation of the binding energy Et and the thermal capture energy Ec, is Ea=0.42 eV in both superlattices. The lowest DX concentration is obtained for the case where the only GaAs layers are doped. For the first time, a study of the capture reveals a capture activation energy Ec=0.36 eV, which locates the DX at Et≊60 meV below the conduction miniband. Taking into account the measured energies and trap concentrations, we show that the only observed DX on such structures is due to the silicon diffusion into AlAs layers.
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61.72.jn Color centers
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Photointercalation effect of thin WO3 films

Masahiro Nagasu and Nobuyoshi Koshida

Appl. Phys. Lett. 57, 1324 (1990); http://dx.doi.org/10.1063/1.104231 (2 pages) | Cited 9 times

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It is shown that thin amorphous films of WO3 exhibit a photoinduced reversible coloration in an electrochemical cell of the form quartz/semitransparent Au/ethanol/WO3/In2O3‐coated glass. From measurements of the optical and electrical properties of the films, the coloration is attributed to the formation of HxWO3, presumably due to a photointercalation of protons into WO3 films. This effect is potentially useful for storage, learning, and modulation of two‐dimensional optical information.
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78.66.-w Optical properties of specific thin films
73.61.Ng Insulators
42.79.Vb Optical storage systems, optical disks
42.70.-a Optical materials

Deep levels associated with α and β dislocations in n‐type InP

Alain Zozime and Wolfgang Schröter

Appl. Phys. Lett. 57, 1326 (1990); http://dx.doi.org/10.1063/1.103472 (2 pages) | Cited 9 times

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We describe an experimental method which allows us to investigate α and β dislocations in compound semiconductors separately by deep level transient spectroscopy. We use two linear configurations of hardness indentations surrounding a key‐shaped metal‐insulator‐semiconductor contact on {100} planes of n‐type InP to generate either α or β dislocations beneath the contact. We observe significant differences in the point defect concentration generated by the motion of the two types of dislocations.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

High precision temperature‐ and energy‐dependent refractive index of GaAs determined from excitation of optical waveguide eigenmodes

S. R. Kisting, P. W. Bohn, E. Andideh, I. Adesida, B. T. Cunningham, G. E. Stillman, and T. D. Harris

Appl. Phys. Lett. 57, 1328 (1990); http://dx.doi.org/10.1063/1.103473 (3 pages) | Cited 16 times

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A GaAs‐Al0.22Ga0.78As heterostructure was prepared and used as a multimode optical waveguide. Propagation constants for individual modes were measured by exciting one mode at a time via real‐space surface grating couplers, and the resulting eigenmode distributions were used to obtain the refractive index of GaAs at a matrix of temperatures and photon energies spanning 40 K<T<300 K and 1.40 eV<hν<1.50 eV. Values for dn/dT and the extrapolated refractive index at T=0 K were also obtained. The dominant error source in these measurements was uncertainty in the angular placement of the sample. These measurements agree well with the few pre‐existing temperature‐dependent measurements, but are an order of magnitude more precise.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.79.Gn Optical waveguides and couplers

Arsenic precipitates and the semi‐insulating properties of GaAs buffer layers grown by low‐temperature molecular beam epitaxy

A. C. Warren, J. M. Woodall, J. L. Freeouf, D. Grischkowsky, D. T. McInturff, M. R. Melloch, and N. Otsuka

Appl. Phys. Lett. 57, 1331 (1990); http://dx.doi.org/10.1063/1.103474 (3 pages) | Cited 298 times

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Arsenic precipitates have been observed in GaAs low‐temperature buffer layers (LTBLs) used as ‘‘substrates’’ for normal molecular beam epitaxy growth. Transmission electron microscopy has shown the arsenic precipitates to be hexagonal phase single crystals. The precipitates are about 6±4 nm in diameter with a density on the order of 1017 precipitates per cm3. The semi‐insulating properties of the LTBL can be explained in terms of these arsenic precipitates acting as ‘‘buried’’ Schottky barriers with overlapping spherical depletion regions. The implications of these results on LTBL resistivity stability with respect to doping and anneal temperature will be discussed as will the possible role of arsenic precipitates in semi‐insulating liquid‐encapsulated Czochralski‐grown bulk GaAs.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.61.Ey III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
64.75.-g Phase equilibria

Thermal generation currents in hydrogenated amorphous silicon p‐i‐n structures

R. A. Street

Appl. Phys. Lett. 57, 1334 (1990); http://dx.doi.org/10.1063/1.103475 (3 pages) | Cited 48 times

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Dark conductivity in amorphous silicon p‐i‐n devices arising from thermal generation through bulk defect states is explored. The current decays slowly after a voltage is applied, due to depletion of charge from the undoped layer, and is voltage dependent due to a field‐enhanced generation rate. Creation of metastable bulk defects by light soaking reversibly increases the current. The steady‐state generation current is dervied from the measured relaxation time and depletion charge.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Pz Photoconduction and photovoltaic effects
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Analysis of the two‐dimensional dark currents in quantum well devices

Kevin Brennan and Yang Wang

Appl. Phys. Lett. 57, 1337 (1990); http://dx.doi.org/10.1063/1.103476 (3 pages) | Cited 6 times

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We present approximate analytical expressions for the principal forms of dark current, thermionic emission, and tunneling, which arise within a two‐dimensional quantum well photodetector. A simple closed form expression for the two‐dimensional thermionic emission current is obtained as well as a numerical result for the tunneling current. Though the dark currents are calculated making use of the usual approximation for the wave function of that for an infinite square well, these expressions are expected to yield reasonable estimates. These formulas can be applied to properly assess the resulting dark currents in photodetectors which utilize quantum well states for either detection or multiplication.
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73.50.Pz Photoconduction and photovoltaic effects
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
85.60.Gz Photodetectors (including infrared and CCD detectors)

Kinetics of solid phase epitaxy in thick amorphous Si layers formed by MeV ion implantation

J. A. Roth, G. L. Olson, D. C. Jacobson, and J. M. Poate

Appl. Phys. Lett. 57, 1340 (1990); http://dx.doi.org/10.1063/1.103477 (3 pages) | Cited 53 times

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The kinetics of solid phase epitaxy (SPE) have been measured in MeV ion‐implanted amorphous Si layers up to 5 μm thick. Epitaxial crystallization in these layers occurs at a constant rate throughout the entire film, without loss of interface planarity or competition from random nucleation or twin formation. The activation energy for SPE in thick layers is found to be 2.70 eV, in excellent agreement with the value determined previously in much thinner films. The SPE kinetics are shown not to depend on the implant dose for doses up to 1000 times the threshold for amorphization. The presence of water vapor in the annealing ambient during SPE results in the indiffusion of hydrogen and a concomitant reduction of the SPE growth rate at distances as great as 2 μm from the surface. This effect may have important implications for the development of a microscopic model of the SPE process in silicon.
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81.15.Np Solid phase epitaxy; growth from solid phases
61.72.uf Ge and Si
66.30.J- Diffusion of impurities

Monolithic InGaAs p‐i‐n InP metal‐insulator‐semiconductor field‐effect transistor receiver for long‐wavelength optical communications

V. D. Mattera, A. Antreasyan, P. A. Garbinski, H. Temkin, N. A. Olsson, and J. Filipe

Appl. Phys. Lett. 57, 1343 (1990); http://dx.doi.org/10.1063/1.103478 (2 pages)

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We have fabricated a monolithically integrated p‐i‐n field‐effect transistor (FET) receiver consisting of an InGaAs/InP p‐i‐n detector and a high‐speed InP metal‐insulator‐semiconductor field‐effect transistor. The receiver sensitivity of the p‐i‐n FET is −18.2 dBm at a bit rate of 2.4 Gb/s and a wavelength of 1.55 μm.
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85.30.Tv Field effect devices
42.82.-m Integrated optics
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
85.60.-q Optoelectronic devices

Self‐electro‐optic device based on a superlattice asymmetric Fabry–Perot modulator with an on/off ratio ≳100:1

K‐K. Law, R. H. Yan, L. A. Coldren, and J. L. Merz

Appl. Phys. Lett. 57, 1345 (1990); http://dx.doi.org/10.1063/1.103479 (3 pages) | Cited 29 times

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A self‐electro‐optic effect device based on a Fabry–Perot reflection modulator has been demonstrated for the first time. This modulator is a normally‐off high‐contrast asymmetric Fabry–Perot modulator using Wannier–Stark localization in a superlattice. Optical bistability has been achieved with a record‐high on/off ratio of 130:1 at the operating wavelength of 7620 Å. The modulator with an appropriate reverse‐bias voltage supply was connected in series to a silicon photodiode which when illuminated with an appropriate light source acted as a current source load for the modulator.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Hp Optical processors, correlators, and modulators
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
78.20.Jq Electro-optical effects

10 μm infrared hot‐electron transistors

K. K. Choi, M. Dutta, P. G. Newman, M.‐L. Saunders, and G. J. Iafrate

Appl. Phys. Lett. 57, 1348 (1990); http://dx.doi.org/10.1063/1.103480 (3 pages) | Cited 34 times

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A new hot‐electron transistor for 10 μm infrared radiation detection is presented and discussed. The device utilizes an infrared sensitive GaAs/AlGaAs multiple quantum well structure as emitter, a wide quantum well as base, and a thick quantum barrier placed in front of the collector as an electron energy high pass filter. The energy filter selectively permits the higher energy photocurrent to pass to the collector; the lower energy dark current is rejected by the filter, and is drained through the base. The device detectivity, as noted by the collector photocurrent measurements, is much enhanced in comparison with companion infrared photoconductive devices.
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85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ey III-V semiconductors

Low‐loss substrate for microwave application of high‐temperature superconductor films

R. Brown, V. Pendrick, D. Kalokitis, and B. H. T. Chai

Appl. Phys. Lett. 57, 1351 (1990); http://dx.doi.org/10.1063/1.103481 (3 pages) | Cited 16 times

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We have shown that strontium lanthanum aluminate (SrLaAlO4) has considerable potential as a substrate material for high‐temperature superconductor (high Tc) microwave applications. Excellent lattice match is obtainable on a 14° tilt from the c axis. The lattice dimensions encourage ab plane epitaxial growth. The thermal expansion was found to be 7.4×10−6 °C−1. Patterned sputtered niobium resonators on SrLaAlO4 exhibit Q values at 5 K comparable to similar niobium resonators on polycrystalline alumina, (Q≳10 000 from 2 to 15 GHz). Deposited YBa2Cu3O7−x (YBCO) films on this substrate show sharp ac susceptibility transitions indicating good homogeneity and ab plane orientation.
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74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates
65.40.De Thermal expansion; thermomechanical effects
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