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18 Jul 1994

Volume 65, Issue 3, pp. 259-380

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Intensity variation of photoluminescence in InxGa1−xAs/GaAs multi‐quantum‐well structures

Z. S. Piao, H. I. Jeon, S. S. Cha, K. Y. Lim, E.‐K. Suh, and H. J. Lee

Appl. Phys. Lett. 65, 333 (1994); http://dx.doi.org/10.1063/1.112362 (3 pages) | Cited 2 times

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We studied the influence of the sample structure on the photoluminescence intensity in terms of carrier diffusion and transfer phenomena in InxGa1−xAs/GaAs multi‐quantum‐well structures. Carrier injection from the barrier, cap, or buffer layers dominates the generation in the well when the well thicknesses are small and the excitation energy is larger than the band gap of the barrier layer. The carrier transport between wells also plays an important role in the photoluminescence particularly in the shallow wells and can be accounted for by phenomenologically introduced hopping time between wells. The hopping time varies from a few tens of picoseconds to a few hundreds of nanoseconds depending on the well composition and width. The strain relaxation of these strained layer quantum‐well structures also leads to the intensity variation as well as the change in the peak position.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Jk Polymers and organics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Influence of cap layer thickness on optical quality in In0.2Ga0.8As/GaAs single quantum wells

S. M. Wang, J. V. Thordson, T. G. Andersson, S. Jiang, L. X. Yang, and S. C. Shen

Appl. Phys. Lett. 65, 336 (1994); http://dx.doi.org/10.1063/1.112363 (2 pages) | Cited 9 times

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Influences of GaAs cap layer thickness on residual strain in partially relaxed, 25-nm-thick In0.2Ga0.8As/GaAs single quantum wells have been investigated by photoluminescence and photoreflectance at 77 K. It was found that the residual strain increased and the optical quality improved with increasing cap layer thickness. Therefore, both quantum well and cap layer thicknesses determine the optical quality in lattice-mismatched semiconductor heterostructures.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Reduction of zinc diffusion into the collector of InP‐based double heterojunction bipolar transistors grown by organometallic chemical vapor deposition

R. Bhat, M. A. Koza, J.‐I. Song, S. A. Schwarz, C. Caneau, and W.‐P. Hong

Appl. Phys. Lett. 65, 338 (1994); http://dx.doi.org/10.1063/1.112364 (3 pages) | Cited 5 times

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It is shown that the growth of emitter layers of InP/InGaAs/InP double heterojunction bipolar transistors can result in significant Zn diffusion from the base into the collector, with the extent of diffusion depending on the n‐doping level of the emitter. This behavior is explained in terms of nonequilibrium point defects induced by a combination of surface pinning of the Fermi level and n doping. It is also shown that the Zn diffusion can be substantially reduced by using AlInAs, instead of InP, as the emitter layer. The difference in behavior is shown to be at least in part due to the lower diffusivity of group III interstitials in AlInAs. Furthermore, it is shown that the introduction of only 50 nm of AlInAs between the n‐InP emitter and p+‐InGaAs base resulted in a significant reduction of Zn diffusion into the collector.
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85.30.Pq Bipolar transistors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.35.Fx Diffusion; interface formation

As/P interdiffusion in ultrathin InAs/InP strained quantum wells

J. M. Sallese, S. Taylor, H. J. Bühlmann, J. F. Carlin, A. Rudra, R. Houdré, and M. Ilegems

Appl. Phys. Lett. 65, 341 (1994); http://dx.doi.org/10.1063/1.112365 (3 pages) | Cited 9 times

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The intermixing process of ultrathin InAs/InP strained quantum well structures by thermal annealing at 730–830 °C is investigated by photoluminescence measurements. Analyzing the results using a microscopic model, the interdiffusion process is characterized by an activation energy close to 3.8±2.0 eV, leading to an interdiffusion coefficient close to 7±0.5×10−7 cm2/s at 830 °C.
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66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
78.55.Hx Other solid inorganic materials
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Near‐field scanning optical microscopy imaging of individual threading dislocations on relaxed GexSi1−x films

J. W. P. Hsu, E. A. Fitzgerald, Y. H. Xie, and P. J. Silverman

Appl. Phys. Lett. 65, 344 (1994); http://dx.doi.org/10.1063/1.112366 (3 pages) | Cited 28 times

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We have identified individual threading dislocations on relaxed, compositionally graded GexSi1−x structures through simultaneous imaging of topography and photoresponse. The threading dislocations show shallow depressions in surface morphology and a 5%–10% reduction in photoresponse compared with the defect‐free regions. The average spatial extent of the reduced photoresponse is (0.66±0.16) μm, which is larger than the associated morphology. This study further demonstrates the application of near‐field scanning optical microscopy to characterization of electrically active defects. The spatial resolution is ten times higher than conventional optical techniques.
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61.72.Lk Linear defects: dislocations, disclinations
72.40.+w Photoconduction and photovoltaic effects
68.55.-a Thin film structure and morphology

Nature of defects in the Si‐SiO2 system generated by vacuum‐ultraviolet irradiation

K. G. Druijf, J. M. M. de Nijs, E. V. D. Drift, E. H. A. Granneman, and P. Balk

Appl. Phys. Lett. 65, 347 (1994); http://dx.doi.org/10.1063/1.112971 (3 pages) | Cited 20 times

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We have used high‐frequency and quasi‐static capacitance‐voltage measurements to study the properties of interface states generated upon vacuum‐ultraviolet irradiation under positive gate bias followed by neutralization of the holes trapped in the oxide. The data indicate the exclusive generation of fast donor‐type states that anneal at room temperature. We propose that these states explain the turn‐around effect and annealing of positive charge.
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71.55.Jv Disordered structures; amorphous and glassy solids
73.20.At Surface states, band structure, electron density of states
73.61.Ng Insulators
78.70.-g Interactions of particles and radiation with matter

Low‐temperature gettering of trace iron and copper by misfit dislocations in Si/Si(Ge) epitaxy

D. M. Lee and G. A. Rozgonyi

Appl. Phys. Lett. 65, 350 (1994); http://dx.doi.org/10.1063/1.112370 (3 pages) | Cited 5 times

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Two examples are presented to illustrate that transition metallic impurities can be extrinsically gettered during low‐temperature processing, even when they are present at trace background levels. Samples of Si/Si(Ge)/Si epitaxial heterostructures containing interfacial misfit dislocations were studied using cross‐sectional analytical transmission electron microscopy (TEM) after a 700 °C annealing in vacuo. In one example, a trace iron precipitate (∼6.5 nm in diameter) which segregated at an end‐on misfit dislocation was analyzed by nanoprobe x‐ray spectroscopy combined with high‐resolution lattice imaging. This iron‐containing precipitate was cubic and epitaxially aligned with the host Si crystal. In a second example, a trace copper precipitate (∼0.5 μm in diameter) with a disk‐like morphology was identified along a misfit dislocation segment. These results demonstrate the effectiveness of misfit dislocations as extrinsic gettering sites at very low‐impurity levels.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.uj III-V and II-VI semiconductors
81.65.-b Surface treatments

Generation and inhibition of domain movement in semi‐insulating GaAs:Cr

H. C. Ellin, A. Grunnet‐Jepsen, and L. Solymar

Appl. Phys. Lett. 65, 353 (1994); http://dx.doi.org/10.1063/1.112372 (3 pages) | Cited 4 times

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Electric‐field domains in semi‐insulating GaAs:Cr are investigated both by imaging the locally induced birefringence using a transverse electro‐optic configuration and by measuring the dc current flowing through the crystal. It is shown that the formation of domains may be controlled by optical means.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.20.Fm Birefringence
78.20.Jq Electro-optical effects

Electronic properties of InGaP grown by solid‐source molecular‐beam epitaxy with a GaP decomposition source

Tomoya Shitara and Karl Eberl

Appl. Phys. Lett. 65, 356 (1994); http://dx.doi.org/10.1063/1.112373 (3 pages) | Cited 33 times

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We have grown high‐quality In0.48Ga0.52P layers on GaAs(001) substrates using solid‐source molecular‐beam epitaxy. A dimer phosphorous (P2) molecular beam was produced from a GaP decomposition source. The full width at half‐maximum of the (004) double‐crystal x‐ray diffraction peak from a 1.7‐μm‐thick InGaP layer on GaAs(001) substrate was 16 arcsec, which is comparable with the smallest values ever reported. The photoluminescence linewidth at 10 K is 16 meV. Hall measurements are carried out on undoped, Si‐doped, and Be‐doped InGaP layers grown with a 2×1 surface reconstruction. The electron mobilities are comparable to similar InGaP/GaAs layers grown by gas‐source molecular‐beam epitaxy. Undoped InGaP layers grown with a 2×2 reconstruction, however, showed a high resistivity of ≥102 Ω cm at 300 K.
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72.80.Ey III-V and II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
78.55.Cr III-V semiconductors

Semi‐insulating InP grown at low temperature by metalorganic chemical vapor deposition

Nathan F. Gardner, Quesnell J. Hartmann, Stephen A. Stockman, Gregory E. Stillman, Judith E. Baker, Jay I. Malin, and K. C. Hsieh

Appl. Phys. Lett. 65, 359 (1994); http://dx.doi.org/10.1063/1.112374 (3 pages) | Cited 11 times

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The growth of semi‐insulating epitaxial InP layers at low substrate temperature (460 °C) by low‐pressure metalorganic chemical vapor deposition has been demonstrated using CCl4 as a dopant source. The resistivity of the material is a function of diluted CCl4 flow rate used during growth. For flow rates less than 5 sccm the material is n type, but for higher flows the resistivity of the material is approximately 5×109 Ω cm. The semi‐insulating behavior of the material is maintained after annealing at 600 °C. Transmission electron microscopy does not reveal the presence of phosphorus precipitates in as‐grown samples or in samples annealed at 400 and 600 °C. There is significant carbon, hydrogen, and chlorine incorporation in the layers, as measured by secondary ion mass spectrometry. Room‐temperature photoluminescence measurements suggest that nonradiative recombination is significant in the material and increases in samples grown with higher CCl4 flows.
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61.72.uj III-V and II-VI semiconductors
72.80.Ey III-V and II-VI semiconductors
78.55.Cr III-V semiconductors

Transport properties in Tl‐Ba‐Ca‐Cu‐O grain boundary junctions on SrTiO3 bicrystal substrates

E. Sarnelli, P. Chaudhari, W. Y. Lee, and E. Esposito

Appl. Phys. Lett. 65, 362 (1994); http://dx.doi.org/10.1063/1.112376 (3 pages) | Cited 17 times

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We have investigated the electrical properties of Tl‐Ba‐Ca‐Cu‐O high‐Tc superconductor bicrystal grain boundary junctions. The behavior of the transport parameters is very similar to those obtained in YBaCuO7−δ junctions. In particular, the temperature dependence of the critical current and the scaling behavior of the critical current density as a function of the misorientation angle were analyzed. Relatively good control of the transport parameters as a function of the misorientation angle has been achieved. The current‐voltage characteristics showed a resistively shunted junction model‐like behavior at large angles (θ≥20°); at lower angles, the characteristics were more flux‐flow like. Preliminary results on noise characteristics are also presented.
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74.50.+r Tunneling phenomena; Josephson effects
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions

Preparation of PbTiO3 thin films by plasma‐enhanced metalorganic chemical vapor deposition

Eiji Fujii, Atsushi Tomozawa, Satoru Fujii, Hideo Torii, and Ryoichi Takayama

Appl. Phys. Lett. 65, 365 (1994); http://dx.doi.org/10.1063/1.112377 (3 pages) | Cited 2 times

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Thin films of PbTiO3 have been prepared on glass substrate by plasma‐enhanced metalorganic chemical vapor deposition. Lead dipivaloylmethane, and titanium tetraisopropoxide were used as the source materials. High crystalline and tetragonal a‐axis oriented PbTiO3 film was obtained at rf power of 200 W and substrate temperature of 570 °C. The deposition rate of the film was as high as 0.18 μm/min. The film had a smooth surface and a columnar structure. The average columnar diameter was about 80 nm. Dielectric constant and tan δ of the deposited film was 250 and 0.04, respectively. The influence of deposition conditions on deposition rate and film properties has been investigated.
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77.55.-g Dielectric thin films
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Laser‐induced deposition of alumina from condensed layers of organoaluminum compounds and water

J. F. Moore, D. R. Strongin, P. B. Comita, M. W. Ruckman, and Myron Strongin

Appl. Phys. Lett. 65, 368 (1994); http://dx.doi.org/10.1063/1.112378 (3 pages) | Cited 6 times

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The photoassisted deposition of thin aluminum oxide films from layers of trimethylaluminum (TMA), dimethylaluminum hydride, and aluminum hexafluoroacetylacetonate condensed with water on a cold substrate has been investigated. Laser energies of 4.6 or 2.3 eV were used to drive the reactions which led to film growth. Experiments show that clean aluminum oxide films can be synthesized at 80 K by irradiating co‐condensed TMA and H2O with 4.6 eV light. Techniques used to characterize the films include Auger electron spectroscopy and scanning electron microscopy.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Evidence for grain boundary hopping transport in polycrystalline diamond films

B. Fiegl, R. Kuhnert, M. Ben‐Chorin, and F. Koch

Appl. Phys. Lett. 65, 371 (1994); http://dx.doi.org/10.1063/1.112379 (3 pages) | Cited 46 times

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We have investigated electrical transport in undoped diamond films prepared by chemical vapor deposition. Using an electrolytic decoration scheme we prove that currents flow predominantly on grain boundaries. From the temperature and the frequency dependencies we conclude that hopping transport takes place. The conductivity at different temperatures is shown to scale according to a universal curve from a random walk model.
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72.20.Fr Low-field transport and mobility; piezoresistance
71.55.Jv Disordered structures; amorphous and glassy solids

High‐purity vapor phase purification of C60

R. D. Averitt, J. M. Alford, and N. J. Halas

Appl. Phys. Lett. 65, 374 (1994); http://dx.doi.org/10.1063/1.112380 (3 pages) | Cited 6 times

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A method is described which utilizes the difference in vapor pressure between C60 and heavier fullerenes to produce ultrahigh purity C60. Fullerene extract is introduced into one end of a distillation column with a series of evenly spaced perforated baffles inside. The extract is heated to 970 K under high vacuum, and a linear temperature gradient is established along the column. As the mixed fullerene vapor effuses down the column, it becomes enriched in the more volatile species. C60 with a purity of 99.97% has been obtained. This method shows promise in the purification of more exotic fullerene compounds.
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81.10.Bk Growth from vapor
82.80.-d Chemical analysis and related physical methods of analysis
FREE

Erratum: ‘‘Highly sensitive interfacial mass detection using ultracompact waveguiding films’’ [Appl. Phys. Lett. 64, 2791 (1994)]

R. Hoyer, C. Mangold, Ch. Fattinger, M. Heming, B. Danielzik, J. Otto, and M. Lohmeyer

Appl. Phys. Lett. 65, 377 (1994); http://dx.doi.org/10.1063/1.113096 (1 page)

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Abstract Unavailable
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
87.80.-y Biophysical techniques (research methods)
42.79.Pw Imaging detectors and sensors
99.10.Cd Errata

Comment on ‘‘Crystal growth of C60 thin films on layered substrates’’ [Appl. Phys. Lett. 63, 2351 (1993)]

Harald Gaber

Appl. Phys. Lett. 65, 378 (1994); http://dx.doi.org/10.1063/1.112333 (1 page) | Cited 2 times

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Abstract Unavailable
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61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology

Response to ‘‘Comment on ‘Crystal growth of C60 thin films on layered substrates’ ’’ [Appl. Phys. Lett. 65, 378 (1994)]

Katsumi Tanigaki, Sadanori Kuroshima, Jun‐ichi Fujita, and Thomas W. Ebbesen

Appl. Phys. Lett. 65, 379 (1994); http://dx.doi.org/10.1063/1.112334 (2 pages) | Cited 1 time

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61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology
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