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A-SI-F AND A-SI-F-H PREPARED BY ION-BEAM-ASSISTED REACTIVE DEPOSITION

JOURNAL OF APPLIED physics 1992年第4期72卷 1446-1453页

作者： ZHANG, S BRODIE, DE Guelph‐Waterloo Program for Graduate Work in Physics Waterloo Campus Waterloo Ontario N2L 3G1 Canada

a-Si:F and a-Si:F:H films have been prepared by ion-beam-assisted deposition using SiF4, SiH4+Ar, or SiF4+SiH4 as the gases for the ion source. Fluorine in a-Si eliminates some dangling bonds, increases the optical gap, and decreases the dark conductivity. The results are influenced mainly by the ion-beam energy used. The a-Si:F films do not exhibit an activated conductivity even up to 150-degrees-C, and no photoconductivity could be detected. However, film properties were significantly improved when a very small amount of H was added to the a-Si:F and much less than 1 at. % H produced films that were photoconducting and had activated conductivities. The properties of these a-Si:F:H are strongly dependent on both the fluorine concentration C(F) and the hydrogen concentration C(H). The deposition rate decreases with increasing SiF4 content in the source gas, and neither C(F) nor C(H) vary linearly with the change in the source gas ratio SiH4/(SiF4+SiH4). Hence, C(H) must be known and controlled in order to evaluate the effect of fluorine on the film's properties. By studying a series of a-Si:F:H samples containing the same C(H), it is noted that incorporating some F does improve the film's electrical properties. Annealing experiments suggest that an observed peak at 2100 cm-1 in the IR spectra of these a-Si:F:H films is not completely due to SiH2, as has been suggested by others.

关键词： AMORPHOUS SEMICONDUCTORS SILICON FLUORINE ADDITIONS HYDROGEN ADDITIONS ENERGY BEAM DEPOSITION FILMS ION BEAMS PHOTOCONDUCTIVITY ELECTRIC CONDUCTIVITY THIN FILMS

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LORENTZIAN CONTRIBUTIONS TO X-RAY LINESHAPES IN SI(LI) SPECTROSCOPY

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X-RAY SPECTROMETRY 1992年第5期21卷 223-227页

作者： CAMPBELL, JL WANG, JX Guelph Waterloo Program for Graduate Work in Physics Department of Physics University of Guelph Guelph Ontario N1G 2W1 Canada

If the lineshape response of a Si(Li) detector is measured using monoenergetic x-rays provided by a monochromator, it must be convoluted by a Lorentzian of appropriate width in order to represent the lineshape encountered in directly measured x-ray spectra. It is shown that the Lorentzian component is responsible for a significant fraction of low-energy peak tailing, a phenomenon usually attributed to detector imperfections.

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DENSITY-FUNCTIONAL THEORY OF THE WATER LIQUID VAPOR INTERFACE

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MOLECULAR physics 1992年第3期76卷 709-735页

作者： YANG, B SULLIVAN, DE TJIPTOMARGO, B GRAY, CG Guelph-Waterloo Programme for Graduate Work in Physics Department of Physics University of Guelph Guelph ON N1G 2W1 Canada

An extended mean-field density-functional theory of the liquid-vapour interface of water is described. The theory generalizes standard mean-field theories of inhomogeneous molecular fluids by including quadratic orders of the anisotropic component of the intermolecular pair potential in the free energy functional. The pair interaction is modelled by an isotropic plus point dipolar and quadrupolar potential. Analysis shows that dipole-quadrupole coupling terms in the potential are responsible for inducing spontaneous polarization at the liquid-vapour interface. The direction of the surface polarization is determined by the sign of the axial component of the molecular quadrupole tensor, as in the earlier phenomenological theory of Stillinger and Ben-Naim. Explicit calculations are performed using molecular interaction parameters given by the TIP4P potential model for water, employed in recent computer simulations of the water interface by Wilson, Pohorille and Pratt. The preferred molecular orientations at the interface predicted by the theory are analysed in detail and compared with previous simulation results.

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PHOTOCONDUCTING TIO2 PREPARED BY SPRAY PYROLYSIS USING TICL4

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THIN SOLID FILMS 1992年第2期213卷 265-270页

作者： ZHANG, S ZHU, YF BRODIE, DE Guelph-Waterloo Program for Graduate Work in Physics University of Waterloo Waterloo Ontario N2L 3G1 Canada

TiO2 was prepared by the oxidation of TiCl4 at relatively low deposition temperatures using spray pyrolysis. For a fixed carrier gas (N2) flow rate, the substrate temperature is the critical parameter determining the film properties. Films made near 595 K contain only the anatase phase, adhere well to the glass substrate, and have a relative optical transmission of about 75% (between 450 and 850 nm), the value one calculates for the non-absorbing anatase phase in this region. These films have an absorption edge characteristic of a direct gap semiconductor with allowed transitions and optical gaps of 3.5-3.7 eV, depending on the porosity. At higher substrate temperatures (above 635 K), the resulting films have a cloudy appearance and they contain both the rutile and the anatase modifications, confirmed by X-ray diffraction. Lower temperature substrates reduce the deposition rate and yield more porous films. For the pure anatase films, the dark conductivities are about one order of magnitude larger, and the photoconductivity is about one order of magnitude smaller when measured with the sample in air, than those observed when the sample is in a vacuum. When the samples are in a vacuum, the conductivities of the clear films increase by about two orders of magnitude (from about 10(-10) to about 10(-8) S cm-1) when illuminated with light from an electrically programmable read-only memory eraser (mercury light), which gives an intensity of about 30-mu-w cm-2 at the sample. The photoresponse has two parts;the fast portion rises in less than 1 s to 99% of its final value, followed by a small slow rise portion. The slow response, which is more pronounced in the decay process, is interpreted as being due to the presence of surface trapping states.

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SPECTROSCOPIC DETECTION OF THE A(V=2) LEVEL OF (HED)-HE-4

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JOURNAL OF CHEMICAL physics 1992年第4期96卷 2540-2543页

作者： TOKARYK, DW BROOKS, RL Guelph‐Waterloo Program for Graduate Work in Physics University of Guelph Guelph Ontario N1G 2W1 Canada

A new near infrared emission spectrum of (HeD)-He-4 has been recorded at 4.2 K during proton irradiation of a mixed sample of helium gas and solid deuterium. The upper state of the transitions is an admixture of the accidentally degenerate D(2)SIGMA+ (upsilon = 0) and C(2)SIGMA+ (upsilon = 3) levels. The lower state is the previously unobserved A(2)SIGMA+ (upsilon = 2) level. The observation of this levels allows for evaluation of the rotational constants B2" and D2" for the A(2)SIGMA+ state, and for a better estimate of the vibrational parameters omega(e)" and omega(e)"-CHI(e)".

关键词： HELIUM 4 HELIUM COMPOUNDS DEUTERIUM COMPOUNDS VIBRATIONAL STATES EMISSION SPECTRA INFRARED SPECTRA NEAR INFRARED RADIATION ULTRALOW TEMPERATURE PHYSICAL RADIATION EFFECTS PROTONS GASES SOLIDS MIXTURES ROTATIONAL STATES

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TRANSPARENT CONDUCTING ZNO FILMS DEPOSITED BY ION-BEAM-ASSISTED REACTIVE DEPOSITION

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THIN SOLID FILMS 1992年第1期213卷 109-112页

作者： ZHANG, DH BRODIE, DE Guelph-Waterloo Program for Graduate Work in Physics University of Waterloo Waterloo Ontario N2L 3G1 Canada

Highly transparent conducting ZnO films have been deposited using ion-beam-assisted reactive vacuum deposition. The zinc deposition rate was controlled by adding gallium to the zinc in an open Al2O3 crucible source. Oxygen was introduced into the system via a separate controlled leak and reacted with the zinc on the substrate. Mechanically stable polycrystalline conducting ZnO films having a preferred orientation were deposited with resistivities in the range from 4.0 x 10(-6) to 9.0 x 10(-6) OMEGA-m, with carrier densities of more than 2 x 10(26) m-3 and Hall mobilities between 2.8 X 10(-3) and 4.0 x 10(-3) m2 V-1 s-1. The average transmission exceeded 90% for films 350 nm thick in the wavelength range of the visible spectrum.

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RAMAN AND FAR-INFRARED SPECTRA OF CYANAMIDE AT 20-K AND 90-K - ATOM ATOM POTENTIALS AND LATTICE FREQUENCIES

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JOURNAL OF RAMAN SPECTROSCOPY 1992年第8期23卷 465-469页

作者： TORRIE, BH Guelph-Waterloo Program for Graduate Work in Physics Waterloo Campus University of Waterloo Waterloo Ontario N2L 3G1 Canada

The Raman and infrared spectra of cyanamide have been remeasured at lower temperatures (20 K) and higher laser powers (for the Raman). The recently obtained structure of cyanamide was used as a basis for calculations of the lattice dynamics. Standard models using atom-atom potentials of the exp - 6 form, an exponentially decaying attractive potential for the hydrogen bond and distributed dipoles on the atoms, gave good fits to the structural parameters and, with scaling, gave moderately good values for the lattice frequencies provided that it was assumed that the modes associated with librations about the long axis of the molecule were not observed.

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CRYSTALLIZATION PROPERTIES OF A SUPERCOOLED METALLIC LIQUID

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JOURNAL OF CHEMICAL physics 1992年第1期96卷 513-516页

作者： QI, DW LU, J WANG, S Guelph‐Waterloo Program for Graduate Work in Physics Waterloo Campus University of Waterloo Waterloo Ontario Canada N2L 3G1

With the aid of molecular-dynamics technique, a calculation of the thermodynamic and structural properties of the crystallization of a supercooled metallic liquid is presented. The calculated results demonstrate a number of features of this crystallization. It now appears that the transition associated with this crystallization is a first-order-like phase transition in the Ehrenfest scheme.

关键词： CRYSTALLIZATION SUPERCOOLED LIQUIDS LIQUID METALS MOLECULAR DYNAMICS CALCULATIONS THERMODYNAMICS STRUCTURE FACTORS PHASE TRANSFORMATIONS MELTING POINTS KINETIC ENERGY COULOMB FIELD DISTRIBUTION FUNCTIONS

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A NEW SPECTRALLY RESOLVED CONFOCAL SCANNING LASER MICROSCOPE

A NEW SPECTRALLY RESOLVED CONFOCAL SCANNING LASER MICROSCOPE

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CONF ON SCANNING MICROSCOPY INSTRUMENTATION

作者： BOWRON, JW DAMASKINOS, S DIXON, AE Guelph-Waterloo Program for Graduate Work in Physics Waterloo Campus University of Waterloo Waterloo N2L 3G1 ON Canada

ISBN: (纸本)0819406848

We have developed a spectrally resolved confocal microscope with high photon efficiency for photoluminescence and fluorescence measurements. A scanning grating is placed inside the detection arm of the microscope so that the diffraction-limited spot on the sample acts like the entrance slit, and the detector pinhole acts like the exit slit of a standard monochromator. The pinhole also performs the same function as the detector pinhole in a standard confocal microscope. This arrangement has better photon efficiency than focusing the light from the detector pinhole of a standard confocal scanning laser microscope onto the entrance slit of a grating monochromator. This configuration also produces higher spectral resolution and is more flexible than one in which bandpass filters are placed in the detection arm. The microscope is described and measurements of the spectral and axial resolutions are presented. Axial resolution measurements were made using a planar sample that is both reflecting and photoluminescent. Spectrally-resolved photoluminescence and fluorescence images are presented. © 1992 SPIE. All rights reserved.

关键词： Scanning

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A NEW TRANSMISSION AND DOUBLE REFLECTION SCANNING BEAM CONFOCAL MICROSCOPE - APPLICATIONS IN TRANSMISSION

A NEW TRANSMISSION AND DOUBLE REFLECTION SCANNING BEAM CONFO...

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CONF ON SCANNING MICROSCOPY INSTRUMENTATION

作者： DIXON, AE DAMASKINOS, S ATKINSON, MR CAO, LH Guelph-Waterloo Program for Graduate Work in Physics Waterloo Campus University of Waterloo Waterloo N2L 3G1 ON Canada Department of Physics Nanjing University Nanjing Jiangsu Province 210008 China

ISBN: (纸本)0819406848

A new confocal scanning beam transmission and reflection microscope is described. The new microscope uses the same detector for both transmitted-light and reflected-light images. The transmitted beam is re-injected into the optical path of the microscope parallel to the reflected beam and the same scanning mirrors are used to descan the two beams. A set of identical objective lenses collect reflected and transmitted light from both the top and bottom of the specimen, recording images with perfect registration. Several images of biological and semiconductor specimens are presented that illustrate the advantages of confocal transmission microscopy. The first scanning-beam confocal transmitted-light differential phase contrast image is also presented. © 1992 SPIE. All rights reserved.

关键词： Microscopes

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