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8 Apr 1991

Volume 58, Issue 14, pp. 1455-1568

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High‐resolution x‐ray diffraction of InAlAs/InP superlattices grown by gas source molecular beam epitaxy

J. C. P. Chang, T. P. Chin, K. L. Kavanagh, and C. W. Tu

Appl. Phys. Lett. 58, 1530 (1991); http://dx.doi.org/10.1063/1.105168 (3 pages) | Cited 8 times

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Structural properties of InAlAs/InP superlattices grown by gas source molecular beam epitaxy on (001)InP were investigated extensively with high‐resolution x‐ray diffraction. Very high quality material was obtained as indicated by narrow peak widths, numerous satellite peaks, and distinct Pendellosung fringes. Intermixing of group‐V elements at each interface was quantified by dynamical simulations of (004), (002), and (115) reflections. The accuracy of the fits to both peak positions and peak intensities for all three reflections provides strong evidence for the proposed four‐layer periodic structure.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
68.35.Fx Diffusion; interface formation

Application of superlattice bandpass filters in 10 μm infrared detection

K. K. Choi, M. Dutta, R. P. Moerkirk, C. H. Kuan, and G. J. Iafrate

Appl. Phys. Lett. 58, 1533 (1991); http://dx.doi.org/10.1063/1.105169 (3 pages) | Cited 10 times

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Recently, experimental evidence has revealed that the energy distribution of the dark current in a typical multiple quantum well GaAs infrared detector is extremely broad, in contrast to the narrowly distributed photocurrent. In this letter, we present the current transfer ratio of an infrared hot‐electron transistor with a superlattice collector filter. From the current transfer characteristics, we demonstrate that the superlattice is able to collect electrons with specific energy against a broad background. The energy filtering characteristics can be attributed to the underlying band structure of the superlattice. When the filter is applied to infrared radiation detection, the detectivity of the transistor is improved.
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73.40.Gk Tunneling
85.60.Gz Photodetectors (including infrared and CCD detectors)
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ey III-V semiconductors

The effect of oxygen on the thermal stability of Si1−xGex strained layers

D. B. Noble, J. L. Hoyt, W. D. Nix, J. F. Gibbons, S. S. Laderman, J. E. Turner, and M. P. Scott

Appl. Phys. Lett. 58, 1536 (1991); http://dx.doi.org/10.1063/1.105170 (3 pages) | Cited 10 times

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The thermal stability of Si1−xGex strained layers containing 2×1020 oxygen atoms/cm3 is compared with that of similar layers (same Ge fraction and film thickness) containing more than two orders of magnitude less oxygen. For the layers with high oxygen levels, no misfit dislocations were found in films as thick as two times the theoretical equilibrium critical thickness, after annealing at 850 °C for 4 min. In contrast, dislocations were found in the layers with low oxygen levels at thicknesses very near the equilibrium critical thickness after the same anneal. X‐ray measurements of lattice constants in high and low oxygen films of similar Ge content indicate that oxygen does not substantially change the amount of strain in the layers. Oxygen appears to impede the kinetics of dislocation formation.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.Nq Composition and phase identification
66.30.Lw Diffusion of other defects

Patterning and characterization of large‐area quantum wire arrays

K. Ismail, M. Burkhardt, Henry I. Smith, N. H. Karam, and P. A. Sekula‐Moise

Appl. Phys. Lett. 58, 1539 (1991); http://dx.doi.org/10.1063/1.105171 (3 pages) | Cited 5 times

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Large‐area arrays of parallel quantum wires of 30–80 nm width are achieved using a combination of x‐ray lithography, wet chemical etching, and low‐pressure metalorganic vapor phase epitaxy. The quantum wires are characterized using low‐temperature photoluminescence and magnetotransport measurements. The quantum confinement is reflected in a clear blue shift in the luminescence peak, and in deviation from the periodicity of the Shubnikov–de Haas oscillations as a function of inverse magnetic field.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.55.Cr III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Electrical properties of selectively grown homoepitaxial diamond films

S. A. Grot, C. W. Hatfield, G. Sh. Gildenblat, A. R. Badzian, and T. Badzian

Appl. Phys. Lett. 58, 1542 (1991); http://dx.doi.org/10.1063/1.105172 (3 pages) | Cited 40 times

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Boron‐doped homoepitaxial diamond films were selectively grown using sputtered SiO2 as a masking material. Uniform thickness, down to 50 nm, over a large area can be achieved with this technique. Hall mobility of selectively grown films is comparable to that of high‐pressure high‐temperature synthetic bulk diamond with a corresponding carrier concentration.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.30.Tv Field effect devices
85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices)
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Calibration of the isolated oxygen interstitial localized vibrational mode absorption line in GaAs

M. Skowronski, S. T. Neild, and R. E. Kremer

Appl. Phys. Lett. 58, 1545 (1991); http://dx.doi.org/10.1063/1.105173 (3 pages) | Cited 3 times

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A series of isochronal annealing experiments have been performed on bulk GaAs crystals doped with oxygen. Two centers induced by oxygen, the isolated oxygen interstitial (Oi) and the gallium‐oxygen‐gallium (Ga‐O‐Ga) defect, most likely due to oxygen interstitial‐arsenic vacancy complex, were monitored using localized vibrational mode absorption. The Ga‐O‐Ga center dissociates at temperatures above 650 °C resulting in an increase of the Oi concentration. Using the known oscillator strength of Ga‐O‐Ga transition, the calibration factor between integrated absorption and concentration of isolated oxygen interstitial was determined to be 8×1016 cm−1. The observed increase of absorption bands of both defects after high‐temperature annealing indicates that other types of oxygen‐containing defects are present.
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78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
61.72.jd Vacancies
61.72.jj Interstitials

Optical switching of a new middle trace in an optically controlled parallel resonant tunneling device−Observation and modeling

S. C. Kan, S. Sanders, G. Griffel, G. H. Lang, S. Wu, and A. Yariv

Appl. Phys. Lett. 58, 1548 (1991); http://dx.doi.org/10.1063/1.105174 (3 pages) | Cited 3 times

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Optical switching of a new middle trace observed in an optically controlled parallel resonant tunneling (OPT) device is demonstrated. A circuit model for the OPT is developed. The circuit model satisfactorily explains the existence of the middle trace and its optical switching.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.40.+w Photoconduction and photovoltaic effects
72.20.Ht High-field and nonlinear effects

Photovoltaic GaAs quantum well infrared detectors at 4.2 μm using indirect AlxGa1−x barriers

B. F. Levine, S. D. Gunapala, and R. F. Kopf

Appl. Phys. Lett. 58, 1551 (1991); http://dx.doi.org/10.1063/1.105175 (3 pages) | Cited 40 times

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We have demonstrated the first bound to continuum state GaAs/AlxGa1−xAs quantum well infrared detector which has a peak response λp=4.2 μm in the center of the midwavelength (λ=3–5 μm) infrared band. Although the detector uses indirect AlxGa1−xAs barriers, excellent hot‐electron transport and a high detectivity D∗λ=1012 cm√Hz/W were achieved.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
73.50.Pz Photoconduction and photovoltaic effects
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

High‐purity InP grown on Si by organometallic vapor phase epitaxy

O. Aina, M. Mattingly, J. R. Bates, A. Coggins, J. O’Connor, S. K. Shastry, J. P. Salerno, A. Davis, J. P. Lorenzo, and K. S. Jones

Appl. Phys. Lett. 58, 1554 (1991); http://dx.doi.org/10.1063/1.105245 (3 pages) | Cited 4 times

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We have grown by organometallic vapor phase epitaxy high‐purity InP on Si substrates using a GaAs intermediate layer. The InP layers exhibit residual electron concentration as low as 5×1014 cm−3 and electron mobilities as high as 4000 and 25 000 cm2/V s at 300 and 77 K, respectively. The achieved InP quality is dependent on the GaAs intermediate layer thickness. These excellent electrical properties are due to high crystal qualities as evidenced by x‐ray rocking curve half width as low as 215 arcsec and defect densities on the order 108 cm−2. p/n junctions, with ideality factors as low as 1.6 and low leakage currents, confirm the device quality of this material.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Surface outgrowth problem in c‐axis oriented Y‐Ba‐Cu‐O superconducting thin films

R. Ramesh, A. Inam, D. M. Hwang, T. D. Sands, C. C. Chang, and D. L. Hart

Appl. Phys. Lett. 58, 1557 (1991); http://dx.doi.org/10.1063/1.105176 (3 pages) | Cited 7 times

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The origin of surface outgrowths in c‐axis oriented superconducting Y‐Ba‐Cu‐O thin films has been identified. We find that a,b‐axis regions nucleate heterogeneously at second phase regions and rapidly grow outward, leading to the formation of lenticular‐shaped outgrowths. The second phase has been identified by electron diffraction and high‐resolution electron microscopy to be the Y1Ba3Cu2O7−x phase that forms as microscopic platelet‐shaped precipitates on the a‐b plane. The heterogeneous nucleation of such outgrowths is general and has been observed in both in situ sputtered and laser‐deposited films. It is probably related to the ledge growth mechanism of the c‐axis oriented Y‐Ba‐Cu‐O thin film and to the precise overall composition of the film and needs to be studied in detail in order to produce films with smooth surfaces.
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68.55.-a Thin film structure and morphology
68.35.Rh Phase transitions and critical phenomena
74.78.-w Superconducting films and low-dimensional structures

Optical control of millimeter wave high Tc superconducting quasi‐optical bandpass filters

Dawei Zhang, D. V. Plant, Harold R. Fetterman, Kevin Chou, Shiva Prakash, C. V. Deshpandey, and Rointan F. Bunshah

Appl. Phys. Lett. 58, 1560 (1991); http://dx.doi.org/10.1063/1.105177 (3 pages) | Cited 5 times

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The optical response of YBa2Cu3O7 high Tc superconducting quasi‐optical millimeter wave bandpass filters operating at W band (75–110 GHz) has been investigated under various conditions of illumination. Radiation from a cw Ar+ laser (514.5 nm) and a frequency‐doubled Nd:YAG laser (532.8 nm, 120 ps) was used to induce a shift in the resonant frequency of the filter. A shifted Lorentzian line shape function model was used to estimate the magnitude of the light‐induced changes. Shifts of the filter’s resonance frequency on the order of 0. 1 MHz were induced by the laser effects on the superconductor pair population.
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84.30.Vn Filters
74.78.-w Superconducting films and low-dimensional structures
74.25.N- Response to electromagnetic fields
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices

Proton radiation effects in microwave cavities and ring resonators fabricated from YBa2Cu3O7−δ

B. D. Weaver, J. M. Pond, D. B. Chrisey, J. S. Horwitz, H. S. Newman, and G. P. Summers

Appl. Phys. Lett. 58, 1563 (1991); http://dx.doi.org/10.1063/1.105178 (3 pages) | Cited 7 times

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We report the first radiation effects study on a superconducting ring resonator made from thin‐film YBa2Cu3O7−δ. Exposure to 2 MeV protons causes the superconducting transition temperature Tc to decrease predictably with fluence. For temperatures below about 0.9Tc , there is no significant change in the transmission coefficient, the center frequency, or the quality factor Q of the resonator, even for doses in excess of 4×1016 protons/cm2 (∼0.04 displacements per film atom). Similarly, the low‐temperature surface resistance Rs of an unpatterned film does not change with irradiation. We show that this insensitivity to radiation is not predicted by standard theory, and that the dominant part of Rs at low temperature is the residual resistance R0. Thus any viable theory describing the origin of R0 must, as a criterion, explain the origin of its insensitivity to large irradiation doses. This criterion is used to evaluate theories ascribing R0 to weak links, flux pinning, impurities, and lattice imperfections.
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74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures
61.80.Jh Ion radiation effects

Low‐field flux pinning in twinned and detwinned single crystals of YBa2Cu3O7−x

L. J. Swartzendruber, D. L. Kaiser, F. W. Gayle, L. H. Bennett, and A. Roytburd

Appl. Phys. Lett. 58, 1566 (1991); http://dx.doi.org/10.1063/1.105180 (3 pages) | Cited 14 times

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Flux trapping in single crystals of YBa2Cu3O7−x before and after twin removal has been measured for vortices parallel and perpendicular to the c axis. The results show clearly that, for low applied magnetic fields, twins contribute significantly to flux pinning over the temperature range 60 to 85 K when the vortices are parallel to the twin boundaries (i.e., parallel to the c axis).
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
61.72.Mm Grain and twin boundaries
74.70.-b Superconducting materials other than cuprates
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
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