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3 Jun 1991

Volume 58, Issue 22, pp. 2459-2567

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Triisopropylantimony for organometallic vapor phase epitaxial growth of GaSb and InSb

C. H. Chen, Z. M. Fang, G. B. Stringfellow, and R. W. Gedridge

Appl. Phys. Lett. 58, 2532 (1991); http://dx.doi.org/10.1063/1.104817 (3 pages) | Cited 10 times

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In the past, trimethylantimony (TMSb) has been almost exclusively used as the Sb source in organometallic vapor phase epitaxy (OMVPE). However, TMSb decomposes at relatively high temperatures (above 500 °C). For growth at lower temperatures, TMSb is not an optimum choice. In addition, TMSb decomposition produces methyl radicals, a source for carbon contamination. Thus, it is important to investigate alternative Sb precursors. In this letter, we report the use of a newly developed Sb source, triisopropylantimony (TIPSb), for atmospheric pressure OMVPE. It is found that both GaSb and InSb can be grown with good surface morphologies at temperatures between 430 and 600 °C. The high growth efficiencies indicate that there are few parasitic reactions between TIPSb and trimethylgallium (TMGa) or trimethylindium (TMIn). The GaSb layers grown at 500 °C have background hole concentrations of 2×1016 cm−3. Low‐temperature photoluminescence (PL) measurements indicate that the acceptor is due to Sb vacancies rather than carbon acceptors. The InSb epilayers have electron concentrations of about 5×1016 cm−3 at 77 K and low‐temperature PL shows well‐resolved exciton and acceptor‐related peaks. These results indicate that TIPSb is a viable source for the OMVPE growth of Sb‐containing III‐V semiconductors.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Calculation of direct interband absorption in HgTe by a second‐order k⋅p method

P. Man and D. S. Pan

Appl. Phys. Lett. 58, 2535 (1991); http://dx.doi.org/10.1063/1.104818 (3 pages)

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An 8×8 second‐order k⋅p approach is employed to treat direct interband absorption in HgTe. A detailed first‐principle calculation of the absorption coefficient is performed with no adjustable parameter. Good agreement is found with experimental data up to at least ℏω≊500 meV which corresponds to k≊0.08(2π/a0). Even in the case of HgTe with a Γ6‐Γ8 energy gap as narrow as −120 meV at T=300 K, our full second‐order calculation still improves over the first‐order k⋅p approach by about 17% around λ=10 μm (ℏω=124 meV) and more at shorter wavelengths. Substantial enhancement is expected for a wider energy‐gap (‖Eg‖ ≳ 1 eV) zinc‐blende bulk material. Comparable accuracy of k⋅p calculations for III‐V and II‐VI unstrained superlattices can also be projected under the envelope‐function approximation.
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78.20.Bh Theory, models, and numerical simulation
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.61.Ga II-VI semiconductors

Scanning tunneling optical spectroscopy of semiconductor quantum well structures

L. Q. Qian and B. W. Wessels

Appl. Phys. Lett. 58, 2538 (1991); http://dx.doi.org/10.1063/1.104819 (2 pages) | Cited 6 times

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Scanning tunneling optical spectroscopy has been used to determine the optical properties of semiconductor quantum wells. With this technique, photoenhanced tunneling currents are measured with a scanning tunneling microscope on heterostructures illuminated with monochromatic light. For the InAsxP1−x/InP strained single quantum well structures, the 295 K spectra exhibit well‐resolved transitions attributable to interband transitions involving the heavy‐hole valence band and the n=1 conduction subband. The observed transition energies are in good agreement with values measured using photoconductivity and photoluminescence spectroscopy on the same samples.
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73.40.Gk Tunneling
07.60.Pb Conventional optical microscopes
72.40.+w Photoconduction and photovoltaic effects
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Properties of SiO2/Si/GaAs structures formed by solid phase epitaxy of amorphous Si on GaAs

A. Callegari, D. K. Sadana, D. A. Buchanan, A. Paccagnella, E. D. Marshall, M. A. Tischler, and M. Norcott

Appl. Phys. Lett. 58, 2540 (1991); http://dx.doi.org/10.1063/1.104820 (3 pages) | Cited 36 times

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We have achieved solid phase epitaxy of thin amorphous Si layers on GaAs using in situ plasma processing and subsequent annealing. High‐resolution transmission electron microscopy of the SiO2/Si/GaAs structure shows that a Si layer ≂20 Å thick epitaxially crystallizes on GaAs after annealing at ≂570 °C in N2. Metal‐oxide‐semiconductor capacitors fabricated on these structures confirm the high quality of these interfaces. By comparing a high‐ frequency (100 kHz) capacitance‐voltage curve with a quasi‐static one, interface state densities as low as 4×1012 eV−1/cm−2 were measured on both n‐ and p‐type GaAs.
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84.32.Tt Capacitors
85.40.Ls Metallization, contacts, interconnects; device isolation
81.15.Np Solid phase epitaxy; growth from solid phases

Confocal resonators for measuring the surface resistance of high‐temperature superconducting films

J. S. Martens, V. M. Hietala, D. S. Ginley, T. E. Zipperian, and G. K. G. Hohenwarter

Appl. Phys. Lett. 58, 2543 (1991); http://dx.doi.org/10.1063/1.104821 (3 pages) | Cited 25 times

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A quasioptical technique of measuring superconductor surface resistance using a confocal resonator has been developed. The method has advantages of nondestructive analysis, high sensitivity, easy extension to higher frequencies, convenient experimental setup, and flexibility in sample size. Tl‐Ca‐Ba‐Cu‐O high‐temperature superconducting films have been measured with this technique and the measured surface resistances were less than 0.01 Ω at 36.135 GHz and 77 K. The measurements have been performed from 29 to 39 GHz, and all films showed roughly a quadratic dependence of surface resistance with frequency.
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74.78.-w Superconducting films and low-dimensional structures
78.66.-w Optical properties of specific thin films
78.20.Jq Electro-optical effects

Time‐resolved luminescence spectroscopy of plasma emission from laser ablation of Bi‐Sr‐Ca‐Cu oxide superconductor and related materials

Hiroshi Fukumura, Hiroshi Nakaminami, Shigeru Eura, Hiroshi Masuhara, and Tomoji Kawai

Appl. Phys. Lett. 58, 2546 (1991); http://dx.doi.org/10.1063/1.104822 (3 pages) | Cited 11 times

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Time‐resolved spectroscopy of the plasma state produced by laser ablation of Bi2Sr2Ca1Cu2 oxide, an amorphous solid of the same composition, and unreacted mixture of the components is reported. The difference in the spectra among the samples indicates that the ablation products depend on the chemical structures of the irradiated samples. Effects of the ambient gas revealed that ionic species in the electronic ground states are mainly generated at the initial stage of the ablation, while atomic species are produced by collisions between the surrounding‐gas molecules and plasma plume.
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74.70.-b Superconducting materials other than cuprates
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light

Fast nonlinear photoresponse of current biased thin‐film Bi2Sr2CaCu2O8 to pulsed far‐infrared radiation

P. G. Huggard, Gi. Schneider, T. O’Brien, P. Lemoine, W. Blau, and W. Prettl

Appl. Phys. Lett. 58, 2549 (1991); http://dx.doi.org/10.1063/1.104823 (3 pages) | Cited 19 times

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The response of a polycrystalline thin‐film Bi2Sr2CaCu2O8 superconducting stripe to short‐pulse far‐infrared (λ=447 μm) radiation is reported. Under constant current bias, a photosignal is generated when the maximum zero voltage current is exceeded. Measurements of the sensitivity as a function of temperature, bias current, and intensity reveal the signal source to be nonbolometric. The response is found to obey a (power)1/2 law over more than 2 orders of magnitude. We believe the detection mechanism arises from the interaction of grain boundary Josephson junctions with radiation induced screening currents.
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74.50.+r Tunneling phenomena; Josephson effects
74.78.-w Superconducting films and low-dimensional structures
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.25.Cp Josephson devices

Practical high Tc Josephson junctions and dc SQUIDs operating above 85 K

M. S. Di Iorio, S. Yoshizumi, K‐Y. Yang, J. Zhang, and M. Maung

Appl. Phys. Lett. 58, 2552 (1991); http://dx.doi.org/10.1063/1.105231 (3 pages) | Cited 68 times

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Reproducible high Tc YBa2Cu3O7/Ag/YBa2Cu3O7 Josephson junctions have been fabricated using an entirely in situ step‐edge technique. The junction process requires the deposition of a single high Tc film and the patterning is performed using standard photolithography and ion‐beam etching. The junctions exhibit a well‐defined supercurrent from 4.2 to 87 K and the ac Josephson effect is observed up to 80 K in response to microwave radiation. dc SQUIDs have been fabricated and show the expected periodic modulation of the critical current in a magnetic field at temperatures ranging from 4.2 to 85.7 K. All of the 56 devices fabricated and measured to date show a well‐defined supercurrent from 4.2 to over 77 K.
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74.50.+r Tunneling phenomena; Josephson effects
74.78.-w Superconducting films and low-dimensional structures
85.25.Cp Josephson devices
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Submicron YBa2Cu3O7−δ grain boundary junction dc SQUIDs

M. Kawasaki, P. Chaudhari, T. H. Newman, and A. Gupta

Appl. Phys. Lett. 58, 2555 (1991); http://dx.doi.org/10.1063/1.104824 (3 pages) | Cited 26 times

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We have fabricated and measured the properties of micron‐size single grain boundary junctions and dc superconducting quantum interference devices (SQUIDs). The width of the junctions was varied between 0.25 and 2 μm. The junctions were formed in c‐axis oriented epitaxial films with a single 24° tilt boundary. They were fabricated using electron beam lithography and ion milling. All of the junctions operate at 77 K. The noise properties of SQUIDs made of these junctions have been characterized. They show a significant 1/f component which is comparable to published values. However, the white noise level, 3×10−31 J/Hz measured at 77 K, is the lowest ever reported.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
74.40.-n Fluctuation phenomena
72.70.+m Noise processes and phenomena
74.50.+r Tunneling phenomena; Josephson effects

Enhancement of optical reflectivity of high Tc superconducting films by ion milling

J. H. Kim, K. Char, I. Bozovic, W. Y. Lee, A. Kapitulnik, and J. S. Harris

Appl. Phys. Lett. 58, 2558 (1991); http://dx.doi.org/10.1063/1.104825 (3 pages)

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We report optical reflectivity data of several representative high Tc superconducting films before and after ion milling. A significant enhancement of optical reflectivity after ion milling of a few thousand Å is observed. We observed that features associated with a‐axis texture vanished after ion milling, resulting in pure c‐axis films. This suggests that a‐axis grains reside mostly near the surface in post‐annealed high Tc superconducting films. The fact that highly oriented c‐axis films can be retained even after post‐annealing (for raising Tc) may be important for practical applications.
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81.40.Tv Optical and dielectric properties related to treatment conditions
74.70.-b Superconducting materials other than cuprates
74.78.-w Superconducting films and low-dimensional structures
78.66.-w Optical properties of specific thin films

Terahertz surface impedance of thin YBa2Cu3O7 superconducting films

Martin C. Nuss, Keith W. Goossen, Paul M. Mankiewich, and Megan L. O’Malley

Appl. Phys. Lett. 58, 2561 (1991); http://dx.doi.org/10.1063/1.104826 (3 pages) | Cited 20 times

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Using coherent terahertz time‐domain spectroscopy, we measure the surface impedance of 500‐Å‐thick unpatterned superconducting YBa2Cu3O7 films in the normal and the superconducting state. Both real and imaginary parts of the surface impedance are measured simultaneously from the amplitude and phase changes of the terahertz bandwidth pulses transmitted through the superconducting films.
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74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Investigation of the thermalization of sputtered atoms in a magnetron discharge using laser‐induced fluorescence

W. Z. Park, T. Eguchi, C. Honda, K. Muraoka, Y. Yamagata, B. W. James, M. Maeda, and M. Akazaki

Appl. Phys. Lett. 58, 2564 (1991); http://dx.doi.org/10.1063/1.104827 (3 pages) | Cited 11 times

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The thermalization of sputtered atoms in a magnetron discharge was investigated using laser‐induced fluorescence. The results clearly indicated for the first time that the velocity distribution agrees well with the Thompson formula [M. W. Thompson, Philos. Mag. 18, 377 (1968)] for d/λ≪1, while a thermalized component becomes appreciable for d/λ≳1, where d is the distance from the cathode surface and λ is the mean free path of sputtered atoms for collisions with filling gas atoms.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Kn Thermodynamics of plasmas
81.15.Cd Deposition by sputtering
FREE

Comment on ‘‘Mechanism for efficient blue second‐harmonic generation in periodically segmented waveguides’’

John D. Bierlein, J. Bryan Brown, and Carel J. van der Poel

Appl. Phys. Lett. 58, 2567 (1991); http://dx.doi.org/10.1063/1.104828 (1 page) | Cited 1 time

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Abstract Unavailable
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Gn Optical waveguides and couplers
77.80.B- Phase transitions and Curie point
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