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11 May 1992

Volume 60, Issue 19, pp. 2321-2439

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Nonlinear far‐infrared photoacoustic magnetospectroscopy of n‐GaAs at low temperatures

A. Schilz, L. Huber, W. Prettl, and J. Kaminski

Appl. Phys. Lett. 60, 2394 (1992); http://dx.doi.org/10.1063/1.107008 (3 pages) | Cited 2 times

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The far‐infrared magnetoabsorption of shallow donors in n‐GaAs has been investigated as a function of irradiation intensity applying a low‐temperature photoacoustic cell. Optical cross sections and saturation intensities of various optical transitions were quantitatively determined yielding recombination times of excited electrons.
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78.20.Ls Magneto-optical effects
71.55.Eq III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
43.38.+n Transduction; acoustical devices for the generation and reproduction of sound

Gunn oscillations up to 20 GHz optically induced in GaAs/AlAs superlattice

H. Le Person, C. Minot, L. Boni, J. F. Palmier, and F. Mollot

Appl. Phys. Lett. 60, 2397 (1992); http://dx.doi.org/10.1063/1.106984 (3 pages) | Cited 29 times

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Direct observation of Gunn oscillations up to 20 GHz, induced by picosecond light pulses in an undoped GaAs/AlAs superlattice, is reported. They are obtained in the superlattice growth direction and from 7 K up to room temperature. The frequency is strongly dependent on the applied bias voltage and on the photoexcited carrier density. The oscillation frequency and the mode of operation are modeled by a classical numerical simulation.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Pz Photoconduction and photovoltaic effects

Direct measurement of piezoelectric field in a [111]B grown InGaAs/GaAs heterostructure by Franz–Keldysh oscillations

H. Shen, M. Dutta, W. Chang, R. Moerkirk, D. M. Kim, K. W. Chung, P. P. Ruden, M. I. Nathan, and M. A. Stroscio

Appl. Phys. Lett. 60, 2400 (1992); http://dx.doi.org/10.1063/1.106985 (3 pages) | Cited 19 times

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We report the first photoreflectance measurement of strain‐induced piezoelectric field in a (111)B InGaAs/GaAs structure. The InGaAs quantum well was pseudomorphically grown in the undoped regions of a GaAs undoped–heavily doped structure. Four structures, two each with the same layer structures but different orientation, (111)B and (100), were used in this study. The electric fields in the undoped GaAs region were measured by Franz‐Keldysh oscillations in photoreflectance. All the samples have a surface barrier height of about 0.7 eV. However, the measured electric field is 30% stronger in the (111)B sample compared to the (100) sample. We attribute this difference to the strain‐induced electric field in the (111)B sample. The piezoelectric field in (111)B strained In0.15Ga0.85As obtained in this measurement is 2.2±0.5×105 V/cm, which agrees very well with theory.
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77.65.-j Piezoelectricity and electromechanical effects
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Simultaneous detection of optical constants ϵ1 and ϵ2 by Brewster angle reflectivity measurements

N. Dietz and H. J. Lewerenz

Appl. Phys. Lett. 60, 2403 (1992); http://dx.doi.org/10.1063/1.106986 (3 pages) | Cited 5 times

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A new method for determination of the dielectric function ϵ is presented. The experiment is based on the simultaneous measurement of the Brewster angle φB and the reflectivity Rp for light polarized parallel to the plane of incidence. ϵ1 and ϵ2 as a function φB and Rp were calculated and the results plotted as contour plots with the optical constants as parameters. Spectral measurements yield ϵ1 and ϵ2 as a function of photon energy. Results obtained on GaAs are evaluated and correspond well to literature data.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Comparative study of interface structure in GaAs/AlAs superlattices grown by molecular beam epitaxy on (001) GaAs substrates misoriented towards (111)Ga or (111)As plane

A. Poudoulec, B. Guenais, C. D’Anterroches, P. Auvray, M. Baudet, and A. Regreny

Appl. Phys. Lett. 60, 2406 (1992); http://dx.doi.org/10.1063/1.106987 (3 pages) | Cited 6 times

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The interface morphology of GaAs/AlAs superlattices grown by molecular beam epitaxy on (001) misoriented GaAs substrates has been investigated using high‐resolution transmission electron microscopy observations. We show that the misorientation towards (111)Ga or (111)As plane leads to the same interfacial structure: monolayer height steps and terrace width variations are observed. But the results reveal that the misorientation towards the (111)Ga plane is the most favorable to a regular growth of superlattice structures, because the higher degree of correlation between the interfaces resulting from a smoothing of step edges.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
68.35.Fx Diffusion; interface formation

Two‐dimensional quantum size effect on the internal photoemission

Benjamin S. M. Lin and J. Hwang

Appl. Phys. Lett. 60, 2409 (1992); http://dx.doi.org/10.1063/1.106988 (3 pages) | Cited 2 times

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A two‐dimensional (2D) quantum size concept is introduced here for interpreting internal photoemission phenomena. Theoretical results correspond well with published photoyield data for platinum silicide/p‐type silicon Schottky barrier diodes. The difference between the optical barrier height and the thermal barrier height can be physically determined by momentum conservation when photoexcited carriers transport over a Schottky barrier. Finite yield at low photon energies and roll‐off at high photon energies are well characterized by the 2D quantum model.
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79.60.-i Photoemission and photoelectron spectra
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions

Dielectric functions and critical points of strained InxGa1−xAs on GaAs

C. Pickering, R. T. Carline, M. T. Emeny, N. S. Garawal, and L. K. Howard

Appl. Phys. Lett. 60, 2412 (1992); http://dx.doi.org/10.1063/1.106989 (3 pages) | Cited 20 times

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Dielectric function spectra of strained InxGa1−xAs (x≤0.25) epilayers on GaAs are presented for the first time, together with spectra of relaxed layers of the same compositions. Critical point energies, obtained by line‐shape fitting to second‐derivative spectroscopic ellipsometry (SE) data, show an increase in the E1, E1+Δ1 splitting with strain, in agreement with theory using GaAs deformation potentials. SE is shown to be capable of determining layer thickness, composition, and strain in this alloy system.
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73.61.Ey III-V semiconductors
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Light emitting charge injection transistor with p‐type collector

Marco Mastrapasqua, Federico Capasso, Serge Luryi, Albert L. Hutchinson, Deborah L. Sivco, and Alfred Y. Cho

Appl. Phys. Lett. 60, 2415 (1992); http://dx.doi.org/10.1063/1.106990 (3 pages) | Cited 7 times

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We report the first realization of a charge injection transistor with a complementary collector. The device is implemented using InGaAs/InAlAs/InGaAs heterostructure material grown by molecular beam epitaxy. Real space transfer of hot electrons into the p‐type collector leads to a luminescence signal arising from the recombination of the injected electrons with holes in the collector active region. The observed on/off ratio in the emitted light power is more than 104 and obeys an exclusive OR function of input voltages. The estimated internal quantum efficiency is as high as 90%.
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85.60.Jb Light-emitting devices
85.60.Dw Photodiodes; phototransistors; photoresistors
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
72.20.Ht High-field and nonlinear effects

Use of tertiarybutylarsine in atomic layer epitaxy and laser‐assisted atomic layer epitaxy of device quality GaAs

Q. Chen, C. A. Beyler, P. D. Dapkus, J. J. Alwan, and J. J. Coleman

Appl. Phys. Lett. 60, 2418 (1992); http://dx.doi.org/10.1063/1.106991 (3 pages) | Cited 11 times

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The use of trimethylgallium (TMGa) and tertiarybutylarsine (TBAs) in atomic layer epitaxy (ALE) and laser‐assisted atomic layer epitaxy (LALE) of GaAs is studied for the first time. TBAs is found to be a direct and suitable replacement for arsine (AsH3) in achieving monolayer self‐limiting growth. Carbon contamination in the GaAs films grown by LALE using TMGa and TBAs is greatly reduced relative to those using TMGa and AsH3. Laser structures single GaAs quantum wells grown by ALE and LALE using TBAs exhibit threshold current density as low as 300 and 520 A/cm2, respectively.
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68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Growth of GaAs and AlGaAs by metalorganic molecular beam epitaxy using tris‐dimethylaminoarsenic

C. R. Abernathy, P. W. Wisk, D. A. Bohling, and G. T. Muhr

Appl. Phys. Lett. 60, 2421 (1992); http://dx.doi.org/10.1063/1.106992 (3 pages) | Cited 20 times

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Due to the extreme toxicity of AsH3, safer alternatives for III–V epitaxy are highly desirable. In addition, the AsH3 molecule is too stable to decompose on the wafer surface at the temperature and pressure conditions normally used during growth by metalorganic molecular beam epitaxy (MOMBE). This requires the use of high‐temperature cracker cells to decompose the AsH3 to elemental As prior to entry to the growth chamber and as a result leads to significant As buildup within the chamber. In this letter we report for the first time MOMBE growth at low temperatures (≤525 °C) using a novel As precursor, tris‐dimethylaminoarsenic (DMAAs) without precracking. Specular surface morphologies were obtained over a wide range of growth temperatures, 375–525 °C, for both GaAs and AlGaAs. Carbon concentrations measured by SIMS analysis in GaAs layers deposited from triethylgallium were lower than those obtained using a similar flux of AsH3, while carbon was reduced more than two orders of magnitude in films grown with trimethylgallium and DMAAs as compared to AsH3. No difference in oxygen content was observed between AlGaAs grown with DMAAs and AsH3.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Growth of DyBa2Cu3O7−x studied by scanning tunneling microscopy

N. Chandrasekhar, V. Agrawal, V. S. Achutharaman, and A. M. Goldman

Appl. Phys. Lett. 60, 2424 (1992); http://dx.doi.org/10.1063/1.106993 (3 pages) | Cited 5 times

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Scanning tunneling microscopy (STM) has been used to investigate the microstructure of DyBa2Cu3O7−x films grown on (100) SrTiO3 by ozone‐assisted molecular beam epitaxy. The surface roughness is found to be higher than that reported for sputtered films of YBa2Cu3O7−x. Intensity oscillations were observed in the specular spot of in situ reflection high energy electron diffraction patterns, a result which suggests that surface smoothness is not a requisite for the observation of such intensity oscillations. The observation of spiral morphology in STM pictures indicates the presence of screw dislocations, in excess of 109 cm−2. A zeroth order approximation has been used to evaluate the shapes of the spirals and reasonable agreement is obtained with experiment.
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74.70.-b Superconducting materials other than cuprates
74.78.-w Superconducting films and low-dimensional structures
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

Metalorganic chemical vapor deposition using a single solution source for high Jc Y1Ba2Cu3O7−x superconducting films

S. Matsuno, F. Uchikawa, S. Utsunomiya, and S. Nakabayashi

Appl. Phys. Lett. 60, 2427 (1992); http://dx.doi.org/10.1063/1.106994 (3 pages) | Cited 25 times

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High Jc Y1Ba2Cu3O7−x superconducting thin and thick films were prepared onto SrTiO3 (100) substrates at 700 °C by metalorganic chemical vapor deposition (MOCVD) technique using a single solution source. A mixture of Y, Ba, and Cu β‐diketonate chelates was dissolved in tetrahydrofuran as a solution source. Zero resistance transition temperature and critical current density at 77 K, 0 T for thin and thick films were 90 K and 2.73×106 A/cm2, 91 K and 3.1×105 A/cm2, respectively. X‐ray diffraction measurement indicated that the thin film grew epitaxially with the c‐axis orientation perpendicular to the surface of the substrate and the thick films mainly consisted of a‐axis orientation.  
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74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Effects of Y2O3 precipitates on critical current anisotropy in YBa2Cu3O7−x thin films prepared by plasma‐enhanced metalorganic vapor deposition

Y. Q. Li, J. Zhao, C. S. Chern, P. Lu, T. R. Chien, B. Gallois, P. Norris, B. Kear, and F. Cosandey

Appl. Phys. Lett. 60, 2430 (1992); http://dx.doi.org/10.1063/1.106995 (3 pages) | Cited 14 times

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Yttrium‐rich YBa2Cu3O7−x thin films containing yttria precipitates with an average size of less than 10 nm and with densities of up to 1024/m3 have been prepared by metalorganic chemical vapor deposition. The field dependence of the critical current density of the yttrium‐rich films with the c‐axis normal to the surface indicates that the precipitates act as effective pinning centers when the magnetic field is perpendicular to the CuO2 planes while their presence has no effect on the critical current density when the magnetic field is parallel to the CuO2 planes. In this case, intrinsic pinning of the weakly coupled CuO2 planes may be the dominant pinning mechanism in c‐axis oriented YBa2Cu3O7−x thin films.
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
74.70.-b Superconducting materials other than cuprates

YBa2Cu3O7 thin‐film step junctions on MgO substrates

J. A. Edwards, J. S. Satchell, N. G. Chew, R. G. Humphreys, M. N. Keene, and O. D. Dosser

Appl. Phys. Lett. 60, 2433 (1992); http://dx.doi.org/10.1063/1.106996 (3 pages) | Cited 24 times

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Josephson junctions have been made by the evaporation of epitaxial YBa2Cu3O7 over steps etched in (001) MgO. Such junctions differ from those grown on perovskite substrates in that the c‐axis of the film grows approximately normal to the local substrate surface, so the junction comprises two tilt grain boundaries. Results are reported for junctions formed by this process which showed Josephson currents at temperatures up to 89 K and resistively shunted junctionlike current‐voltage curves. A weak magnetic field applied normal to the substrate gave Fraunhofer patterns indicative of good current uniformity across the junction. The dc SQUIDs show deep modulation, and promising noise performance.
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85.25.Cp Josephson devices
85.25.Dq Superconducting quantum interference devices (SQUIDs)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
74.70.-b Superconducting materials other than cuprates

Giant magnetoresistance dependence on Ar acceleration voltage in Co9Fe/Cu and Co3Fe/Cu multilayers

Y. Saito, S. Hashimoto, and K. Inomata

Appl. Phys. Lett. 60, 2436 (1992); http://dx.doi.org/10.1063/1.106997 (3 pages) | Cited 17 times

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In relation to theoretical predictions on the importance of randomness at the interface to determine the cause for giant magnetoresistance, argon acceleration voltage (VB) in ion beam sputtering was changed for preparing a set of CoxFe1−x/Cu multilayers. We found that the magnetoresistance as quite sensitive to the argon acceleration voltage and had a maximum around VB=600 V. Perfect antiferromagnetic coupling of the CoxFe1−x layers via thin Cu layers and the oscillation behavior of this indirect exchange coupling with a 12 Å period were observed for VB=600 V. These results suggest the importance of the interface state for giant magnetoresistance in multilayers. We also found that a small saturation field can be induced, which can be explained by the metamagnetic transition associating the relation of Ku≳J/tCoFe.
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75.70.-i Magnetic properties of thin films, surfaces, and interfaces
81.15.Cd Deposition by sputtering
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
FREE

Erratum: ‘‘Heavily Si‐doped GaAs grown by low‐pressure metalorganic chemical vapor deposition using tertiarybutylarsine and silane’’ [Appl. Phys. Lett. 60, 489 (1992)]

S. Chichibu, A. Iwai, S. Matsumoto, and H. Higuchi

Appl. Phys. Lett. 60, 2439 (1992); http://dx.doi.org/10.1063/1.107447 (1 page)

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Abstract Unavailable
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68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
99.10.Cd Errata
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