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Applied Physics Letters

Issue 5 • Date Mar 1975

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Displaying Results 1 - 19 of 19
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • Phase-matching condition for scattering from acoustic surface reflective arrays

    Page(s): 215 - 217
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    A phase-matching condition for scattering from acoustic surface reflective arrays is derived with velocity slowing of the reflective stripes taken into account. Propagation in a periodic region is described in terms of waves with sawtooth-shaped phase fronts. Stored energy is proposed as a mechanism for altering the effective velocity anisotropy between incident and scattered waves. The theory is tested against measured transmission resonances for metallic (Al) gratings on Y-cut LiNbO3. View full abstract»

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  • Effects of flow in aerosol measurements by laser Doppler spectroscopy and its nullification

    Page(s): 218 - 220
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    It is shown that the current autocorrelation function of scattered light from aerosols situated in gas that has macroscopic motion will be strongly affected. The exact autocorrelation function for steady flow is calculated. Experimental results verify the calculated results. Using the measured results and the calculated function one can find the single-particle correlation function and the diffusion coefficient. View full abstract»

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  • Evidence for electronic stopping in ion implantation: Shallower profile of lighter isotope 10B in Si

    Page(s): 221 - 222
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    It has been observed by C-V measurements that randomly implanted 10B has shallower profiles in Si than 11B for the acceleration energy range from 50 to 200 keV. This effect can be explained only in terms of electronic stopping in LSS’s theory. View full abstract»

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  • Starting times of laser-induced intrinsic damage in NaCl

    Page(s): 223 - 226
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    The starting time for laser-induced intrinsic damage in NaCl is calculated as a function of the rms optical field strength at the peak of the laser pulse. Three different damage mechanisms are considered: (i) avalanche ionization for λ⩾1 μ, (ii) five-photon assisted avalanche ionization at λ=0.694 μ, and (iii) three-photon assisted avalanche ionization at λ=0.347 μ. It is shown that the probability to measure the true damage threshold E*th is zero. (E*th is the optical peak field strength of a laser pulse that heats a small sample volume so that the melting point is reached exactly at the end of the pulse.) For this reason a ’’practical’’ damage threshold E*T is defined which is the peak field strength of a pulse that causes damage by melting at the time the laser flux reaches its peak. View full abstract»

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  • A thermal imaging system based on the PrCl3 quantum counter

    Page(s): 226 - 228
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    Ambient-temperature thermal background limited performance has been obtained for a thermal imaging system based on the PrCl3 quantum counter. The principal ’’noise’’ source in the PrCl3 quantum counter is shown to be a pump-induced emission characterized by a radiative lifetime of less than 50 nsec. Using the principle of temporal discrimination for the reduction of noise, a contrast of ∼40% was measured for a temperature difference of ∼5 °C above ambient temperature (23 °C). View full abstract»

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  • p-InP/n-CdS solar cells and photovoltaic detectors

    Page(s): 229 - 230
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    We have prepared p-InP/n-CdS heterodiode photovoltaic detectors with a uniform quantum efficiency of ∼70% for wavelengths between 550 and 910 nm. On a cloudy day in New Jersey, (53 mW/cm2) solar power conversion efficiencies of 12.5% have been measured on cells provided with antireflection coatings. View full abstract»

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  • Optically pumped cw InSb lasers for NO spectroscopy

    Page(s): 231 - 233
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    Tunable cw laser emission has been obtained near 5.3 μm from InSb samples at ∼10 K optically pumped with GaAs, Nd : YAG, and CO lasers. InSb laser thresholds have been determined as a function of incident pump wavelength and applied magnetic fields from 0 to 9.5 kOe. Temperature and magnetic field tuning have been utilized to obtain NO absorption spectra over a 10-cm-1 range. View full abstract»

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  • Amorphous semiconductor threshold on-state properties as functions of decay time, ambient temperature, and polarity

    Page(s): 234 - 237
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    The on-state conductance and radiative emission properties of an amorphous semiconductor threshold switch have been investigated. The transient on-state conductance GT and differential conductance G~T are found to be constant for time intervals τ of up to 120 nsec during which the voltage is below the low-frequency holding voltage but above the knee voltage. The knee voltage is the voltage at which the transient on-state current-voltage curve coalesces into the transient off-state curve in the down-voltage direction. For τ≳120 nsec, GT and G~T vary asymptotically with time. As ambient temperature is increased from 300 to 400 °K, G~T is observed to remain constant or increase slightly as would be expected in dGT/dT for a metal. If the on-state is assumed to have a band gap, conductance vs temperature measurements indicate that the gap would have a value less than 1.2×10-4 eV, and thus for practical purposes the gap could be considered to be essentially zero. The intensity of the nonthermal radiative emission which is observed during the on-state of a threshold event is found to be polarity dependent such that when the Nesa electrode adjacent to the detector is of positive polarity, the intensity of the emission is 25% greater than when the polarity is reversed. These observations are interpreted as indications that the on state is maintained electronically rather than thermally, in a state analogous to a metal or semimetal with a zero indirect electrical band gap but a finite direct optical gap. View full abstract»

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  • Improved optical quality of AgGaS2

    Page(s): 237 - 239
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    Single crystals of AgGaS2 for nonlinear optical applications were grown by the Bridgman-Stockbarger technique. It was possible to prepare 0.5-cm cubes free of lamellar twins from the central region of the boules. Room-temperature absorption of as-grown crystals was below 0.3 cm-1 through the whole transmission range. After an annealing process with additional sulfur, absorption was reduced to α≪0.1 cm-1 in the wavelength range λ=0.9-8.5 μm. View full abstract»

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  • Reliability of DH GaAs lasers at elevated temperatures

    Page(s): 239 - 242
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    Data from accelerated aging tests on continuously operating stripe-geometry double-heterostructure GaAs lasers are presented. By extrapolating data obtained in dry-nitrogen ambients at temperatures of 90, 70, and 50 °C, it is concluded that continuous room-temperature operation of these devices as lasers with power outputs exceeding 1 mW per laser face for times in excess of 100000 h is possible. View full abstract»

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  • Reversible photoinduced change in intermolecular distance in amorphous As2S3 network

    Page(s): 243 - 245
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    A reversible photoinduced change in the intermolecular distance has been observed in a well-annealed As2S3 film using a detailed x-ray diffraction technique. This phenomenon is strongly related to the reversible optical absorption edge shift (i.e., photodarkening) by successive cycles of band-gap illumination and annealing. A quantitative interpretation is given for both phenomena in connection with the pressure-induced optical absorption edge shift. View full abstract»

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  • FM noise of high-efficiency GaAs IMPATT oscillators and amplifiers

    Page(s): 245 - 248
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    It is found experimentally that the FM noise deviation and noise measure of high-efficiency Read-type GaAs oscillators improve with increasing output power, in contrast with the behavior of conventional (flat doping profile) devices of similar technology. It is suggested that this novel potentially attractive feature may be due to tunnel carrier generation in the Read-type device. View full abstract»

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  • Electron trapping at positively charged centers in SiO2

    Page(s): 248 - 250
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    Evidence is presented which indicates that positive oxide charge centers in thin films of thermally grown silicon dioxide are electron traps with an average capture cross section of 3±2×10-13 cm2 at room temperature and at an average oxide field of about 7×105 V/cm. Positive charge centers of other origins are also expected to be electron traps with about the same capture cross section. View full abstract»

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  • Defect structure of degraded heterojunction GaAlAs-GaAs lasers

    Page(s): 250 - 252
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    Transmission electron microscopy has been used to study the defects associated with the degradation of broad-contact geometry double-heterostructure lasers. Two different types of dislocation networks have been observed close to the active region of the degraded device having Burgers vectors of (a/2) 〈011〉 and a〈001〉. Both networks have been shown to be of interstitial character. View full abstract»

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  • Energy transfer from Ce3+ to Tm3+ in borate and phosphate glasses

    Page(s): 253 - 254
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    Energy transfer from Ce3+ to Tm3+ is reported in borate and phosphate glasses. It was found that the 1D23H4 blue emission of thulium could be increased manyfold when excited through 4f-5d absorption of Ce3+. It is suggested that the energy transfer process is of multipolar type. View full abstract»

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  • Single-crystal β-SiC films by reactive sputtering

    Page(s): 255 - 256
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    Single-crystal β-SiO films were deposited by reactive sputtering on α-SiC substrates at temperatures as low as 1150 °C at a growth rate of 3 Å/sec. Elemental Si was used for target material. The carbon was provided by introducing a hydrocarbon gas in the reaction chamber. Initial results indicate that the process is highly promising. View full abstract»

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  • Coherent selective erasure of superimposed volume holograms in LiNbO3

    Page(s): 256 - 258
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    Selective erasure of superimposed holograms recorded in Fe-doped LiNbO3 is reported. This process consists of photoinducing complementary refractive index changes which cancel the previously recorded changes. It can be applied to any stacked hologram in the crystal volume as well as to any part of one selected hologram; in this last case it performs the Boolean operation exclusive or. View full abstract»

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  • Ferromagnetic domain structure of metallic glasses

    Page(s): 259 - 260
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    We have applied the scanning electron microscopy (SEM) technique of Fathers et al. to a study of domain structure in metallic glasses of the form TM0.75P0.16X0.06Al0.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C, or Si. The domain structure is dominated by the presence of a spatially nonuniform uniaxial anisotropy which is related to the flow processes induced by quenching the molten alloy. The existence of both a magnetostrictive and a directional ordering source of anisotropy is indicated. View full abstract»

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Aims & Scope

Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics.

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Editor
Nghi Q. Lam
Argonne National Laboratory