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29 Dec 1986

Volume 49, Issue 26, pp. 1755-1804


Phase matching in symmetrical single‐mode magneto‐optic waveguides by application of stress

H. Dammann, E. Pross, G. Rabe, W. Tolksdorf, and M. Zinke

Appl. Phys. Lett. 49, 1755 (1986); http://dx.doi.org/10.1063/1.97235 (3 pages) | Cited 20 times

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Tuning of the propagation constant difference Δβ=βTM−βTE in single‐mode symmetrical yttrium iron garnet (YIG) film waveguides over a range of 250°/cm by means of external stress is demonstrated. An a posteriori, precise setting of phase match Δβ→0, which is a precondition for nonreciprocal mode coupling type components, can be achieved by this method.
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42.79.Gn Optical waveguides and couplers
78.20.Ls Magneto-optical effects
81.40.Tv Optical and dielectric properties related to treatment conditions

Regenerative amplification of temporally compressed picosecond pulses at 2 kHz

Y. J. Chang, C. Veas, and J. B. Hopkins

Appl. Phys. Lett. 49, 1758 (1986); http://dx.doi.org/10.1063/1.97621 (3 pages) | Cited 14 times

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Regenerative amplification of temporally compressed picosecond pulses is demonstrated in neodymium: yttrium aluminum garnet (Nd:YAG) at 2 kHz. The seed to the regenerative amplifier originates from a chirped cw mode‐locked Nd:YAG laser pulse. The initial 100 nJ ∼80 ps full width at half‐maximum pulses are amplified and temporally compressed to ∼200 μJ/pulse at a repetition rate of 2 kHz with a pulse width of 12 ps.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers

Measurement of air gap thickness underneath an opaque film by pulsed photothermal radiometry

A. C. Tam and H. Sontag

Appl. Phys. Lett. 49, 1761 (1986); http://dx.doi.org/10.1063/1.97236 (3 pages) | Cited 10 times

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We describe an experimental method to detect and measure a thin air gap between an opaque film and a substrate. The method is pulsed photothermal radiometry with signal shape analysis at suitable delayed times. This relies on the use of a short light pulse to heat up the surface of the opaque film by∼10 °C, and detecting the infrared thermal emission from the surface as a function of time for a sufficiently long time. A numerical computation as well as an analytical approximation is developed to explain the dependence of the photothermal radiometry signal shape on the air gap thickness in the range of ten to hundreds of microns. Our work has applications not only for detecting subsurface air gaps and delaminations, but also for measuring the thermal resistance between layers for nondestructive characterization of adhesion bond strengths.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.-a Thin film structure and morphology
07.60.Dq Photometers, radiometers, and colorimeters
62.20.Qp Friction, tribology, and hardness

Nucleation and initial growth of GaAs on Si substrate

S. J. Rosner, S. M. Koch, and J. S. Harris

Appl. Phys. Lett. 49, 1764 (1986); http://dx.doi.org/10.1063/1.97237 (3 pages) | Cited 12 times

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The microstructure of thin layers of GaAs grown on Si substrates at low growth temperatures by molecular beam epitaxy was examined using transmission electron microscopy and MeV 4He+ ion channeling angular scan analysis. Crystalline island formation is observed at temperatures as low as 325 °C, with epitaxial orientation and distinct nucleation habits apparently tied to the symmetry of the misoriented substrate. For films with no exposure to temperatures above 405 °C, the planar strain is found to be compressive, up to a thickness of 100 nm.
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68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Observation of, and bias‐dependent annealing of, a paramagnetic defect possibly unique to thermally grown SiO2

W. E. Carlos

Appl. Phys. Lett. 49, 1767 (1986); http://dx.doi.org/10.1063/1.97238 (3 pages) | Cited 7 times

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The observation of a variant of the Si E′ center which is possibly unique to thin films of SiO2 is reported. This center which has not been reported for bulk a‐SiO2 is detected after x irradiation of films grown on (111) and (100) wafers of silicon. The center contains two threefold coordinated Si atoms with one having axial symmetry and the other having orthorhombic symmetry. Evidence indicates that this defect is very near the Si‐SiO2 interface. The annealing behavior of the defect has a bias dependence which is very similar to that observed for fixed oxide charge in metal‐oxide‐semiconductor devices.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
76.30.Mi Color centers and other defects
61.80.Cb X-ray effects

Epitaxial growth of NiSi2 on ion‐implanted silicon at 250–280 °C

S. W. Lu, C. W. Nieh, and L. J. Chen

Appl. Phys. Lett. 49, 1770 (1986); http://dx.doi.org/10.1063/1.97239 (3 pages) | Cited 18 times

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Striking effects of dopant atoms on the formation of Ni silicides were observed. Epitaxial NiSi2 was found to grow on both BF+2‐ and B+‐implanted (001) and (111)Si at 250–280 °C. The formation of Ni2Si was suppressed. It is conjectured that the presence of dopant atoms may lower the activation energy substantially to promote the formation of epitaxial NiSi2 at low temperatures. The effects may be exploited to grow other epitaxial silicides on silicon at low temperatures.
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81.15.Np Solid phase epitaxy; growth from solid phases
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Interference peaks in double‐crystal x‐ray rocking curves of laser structures

X. Chu and B. K. Tanner

Appl. Phys. Lett. 49, 1773 (1986); http://dx.doi.org/10.1063/1.97240 (3 pages) | Cited 28 times

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Interference peaks in double‐crystal x‐ray rocking curves have been observed in GaAlAs laser structures. The interference has been shown to arise from phase coherence of the x‐ray waves across a thin heteroepitaxial layer sandwiched between two layers of equal composition. It is shown that the interference fringes can be used to measure active layer thicknesses to ±200 Å. This is despite the fact that the active layer peak cannot be resolved in the rocking curve.
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68.55.-a Thin film structure and morphology
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.60.Jb Light-emitting devices

Indium exodiffusion in annealed GaAs:In crystals

S. K. Krawczyk, A. Khoukh, R. Olier, A. Chabli, and E. Molva

Appl. Phys. Lett. 49, 1776 (1986); http://dx.doi.org/10.1063/1.97241 (3 pages)

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In this work, we report on the effect of annealing on the distribution of indium in the surface region of In‐alloyed GaAs crystals. Auger, secondary ion mass spectroscopy, and photoluminescence were used as the analytical tools. It is shown that In migrates and piles up over a depth of several tens or a few hundreds of angstroms from the surface leaving behind an In‐depleted region. The In redistribution results in modifications of the band gap in the surface region of annealed GaAs:In substrates; these modifications take place even at temperatures as low as 400 °C.
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68.35.Fx Diffusion; interface formation
68.35.Dv Composition, segregation; defects and impurities
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
73.20.-r Electron states at surfaces and interfaces

Resonant tunneling hot‐electron transistor with current gain of 5

Toshihiko Mori, Hiroaki Ohnishi, Kenichi Imamura, Syunichi Muto, and Naoki Yokoyama

Appl. Phys. Lett. 49, 1779 (1986); http://dx.doi.org/10.1063/1.97242 (2 pages) | Cited 6 times

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By optimizing its structure, we have improved the current gain and collector‐current peak‐to‐valley ratio of a resonant tunneling hot‐electron transistor. The device has an asymmetric resonant tunneling barrier with an optimal well thickness to attain a higher peak‐to‐valley ratio for the collector current. Also, the device uses a graded collector barrier and decreased base thickness, exhibiting a common emitter current gain of 5.1 (at 77 K), the highest value ever reported for an AlGaAs/GaAs hot‐electron transistor.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
73.40.Gk Tunneling
85.30.De Semiconductor-device characterization, design, and modeling
72.20.Ht High-field and nonlinear effects

Submicron conducting channels defined by shallow mesa etch in GaAs‐AlGaAs heterojunctions

H. van Houten, B. J. van Wees, M. G. J. Heijman, and J. P. André

Appl. Phys. Lett. 49, 1781 (1986); http://dx.doi.org/10.1063/1.97243 (3 pages) | Cited 69 times

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A new approach to the lateral confinement of electrons in the two‐dimensional electron gas of GaAs‐AlGaAs heterojunctions has been developed. The electrons are electrostatically confined by a shallow mesa structure etched in the upper n‐doped AlGaAs layer. This structure is fabricated using electron beam lithography and reactive ion etching. The undoped AlGaAs spacer layer is not removed in order to avoid mobility degradation and channel depletion. Long narrow channels have been made for the study of electrical transport properties. The effective channel width in the submicron range is smaller than the width of the mesa structure. Preliminary low‐temperature magnetoresistance data are presented.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.My Galvanomagnetic and other magnetotransport effects
71.55.Jv Disordered structures; amorphous and glassy solids
81.65.-b Surface treatments

Deep level transient spectroscopy of interfacial traps at ion‐implanted ultrahigh p‐Si Schottky barriers

John H. Slowik and S. Ashok

Appl. Phys. Lett. 49, 1784 (1986); http://dx.doi.org/10.1063/1.97244 (3 pages) | Cited 6 times

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Sequential implantation of Ar and low‐energy H produces a high (0.83 eV), near‐ideal Schottky barrier for Al deposited on p‐Si. Deep level transient spectroscopy (DLTS) measurements reveal majority‐carrier interfacial traps due to the implantation steps. Without H, Ar implantation alone results in an interfacial trap doublet at 0.48 eV with high emission rates. Such samples display an elevated barrier relative to the implanted control samples, but with serious leakage current. When H implant is added, however, only a single interfacial trap, with a very low emission rate, is present at 0.47 eV. Thus DLTS suggests that H may idealize the barrier by substituting interfacial traps having reduced charge transport rate, so that there is less competition with thermionic emission.
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61.80.Jh Ion radiation effects
85.30.Hi Surface barrier, boundary, and point contact devices
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts

Formation of p‐type GaAs layers using Mg+ implantation and capless rapid thermal annealing

A. N. M. Masum Choudhury and C. A. Armiento

Appl. Phys. Lett. 49, 1787 (1986); http://dx.doi.org/10.1063/1.97191 (3 pages) | Cited 6 times

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The enhanced overpressure proximity technique has been applied to the formation of p‐GaAs layers using capless rapid thermal annealing of GaAs implanted with Mg+. Carrier concentrations in excess of 1×1019 cm−3 and excellent hole mobilities have been achieved without a dielectric encapsulant using this annealing method. Implants were performed at 200 or 320 keV with doses of 1×1014 cm−2 or 1×1015 cm−2. Hall measurements have yielded electrical activations as high as 86% and 38% for the low and high dose samples, respectively. Capacitance‐voltage measurements on implanted samples indicate that this annealing technique can be used to control the doping profile for use in the fabrication of devices requiring p‐n junctions.
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81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.40.Rs Electrical and magnetic properties related to treatment conditions
61.72.U- Doping and impurity implantation
72.20.-i Conductivity phenomena in semiconductors and insulators

Deep level transient spectroscopy signature analysis of DX centers in AlGaAs and GaAsP

J. Criado, A. Gomez, E. Muñoz, and E. Calleja

Appl. Phys. Lett. 49, 1790 (1986); http://dx.doi.org/10.1063/1.97192 (3 pages) | Cited 16 times

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The characterization of deep levels generated by donor dopants (DX centers) requires reliable deep level transient spectroscopy (DLTS) data. Because in AlGaAs and GaAsP the electron thermal emission from DX centers produces strong nonexponential capacitance transients, blind DLTS analysis may lead to erroneous trap parameter determinations. In this work the DLTS sampling conditions to be used for proper DX center characterization are examined. It is concluded that, only under constant tb/ta windowing ratios, self‐consistent trap parameters are obtained.
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78.40.Fy Semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Enhanced oxygen diffusion in silicon at thermal donor formation temperature

S.‐Tong Lee and Paul Fellinger

Appl. Phys. Lett. 49, 1793 (1986); http://dx.doi.org/10.1063/1.97193 (3 pages) | Cited 20 times

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From the outdiffusion profiles of oxygen in Czochralski silicon at 500 °C measured with secondary ion mass spectrometry (SIMS), oxygen diffusivities of 2.5–4.0×10−14 cm2 s−1 are deduced, which are enhanced nearly four orders of magnitude relative to the normal diffusivity. Diffusion of implanted oxygen‐18 in float‐zone silicon at 400–525 °C yields SIMS profiles consisting of an exponential decay of oxygen concentration. The exponential profiles of oxygen‐18 above background (1014 cm−3) as deep as 4–16 μm also show direct evidence of enhanced long‐range oxygen diffusion. The results of enhanced oxygen diffusion can be explained with a fast‐diffusing species, which is in dynamical equilibrium with the interstitial oxygen.
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66.30.J- Diffusion of impurities
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
61.72.uf Ge and Si

Symmetry forbidden Raman scattering from (100) surfaces of oxidized Si and Ge

J. C. Tsang

Appl. Phys. Lett. 49, 1796 (1986); http://dx.doi.org/10.1063/1.97194 (3 pages) | Cited 3 times

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Raman scattering excited by light absorbed within 200 Å of the semiconductor surface has been used to characterize changes introduced at (100) surfaces of Si and Ge by oxidation. Oxidation dependent, broad band, first order Raman spectra similar in appearance to the spectra obtained from the amorphous phases of Si and Ge have been observed. These results are obtained for oxide thicknesses up to 1.7 μm without any special sample preparation, suggesting that Raman scattering can be a useful probe of such interfaces.
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81.65.-b Surface treatments
78.30.Hv Other nonmetallic inorganics
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Ja Surface and interface dynamics and vibrations

Plasma sprayed Fe76Nd16B8 permanent magnets

R. A. Overfelt, C. D. Anderson, and W. F. Flanagan

Appl. Phys. Lett. 49, 1799 (1986); http://dx.doi.org/10.1063/1.97195 (3 pages) | Cited 6 times

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Thin coatings (0.16 mm) and thick coatings (0.50 mm) of Fe76Nd16B8 were deposited on stainless‐steel substrates by low pressure plasma spraying. Microscopic examination of the coatings in a light microscope revealed excessive porosity, but good bonding to the substrate. Fracture cross sections examined in a scanning electron microscope showed the grains to be equiaxed and approximately 1 μm or less in diameter in the as‐sprayed condition. The intrinsic coercivities of the as‐sprayed coatings varied from 5.8 to 10.9 kOe. The effects of post‐spray heat treatments on the intrinsic coercivity are also given.
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07.55.Db Generation of magnetic fields; magnets
85.70.-w Magnetic devices
75.50.Vv High coercivity materials
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
81.05.Bx Metals, semimetals, and alloys

Non‐Markovian quantum dynamical equations for modeling electron transport in ultrafast microdevices

J. Lin and L. C. Chiu

Appl. Phys. Lett. 49, 1802 (1986); http://dx.doi.org/10.1063/1.97196 (3 pages) | Cited 6 times

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In ultrasmall devices where the relevant time scale is comparable to the dynamical time scale, the usual Markovian transport theory based on time coarse graining becomes untenable. We present a new non‐Markovian quantum transport formalism that is not only valid in the dynamical regime, but also free from the energy runaway problem plaguing the Markovian theory. Apart from making practical calculations numerically stable, the theory provides the foundation for delineating the range of validity of the classical Boltzmann and Markovian quantum transport.
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72.10.Bg General formulation of transport theory
85.60.-q Optoelectronic devices
85.30.De Semiconductor-device characterization, design, and modeling
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