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  • 1
    Electronic Resource
    Electronic Resource
    Evidence of an interfacial layer formation during rare-earth deposition onto CdTe: The case of Sm (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 237-243 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An interfacial layer (IL), about a nanometer thick, is produced by Sm deposition onto (001) CdTe grown by molecular-beam epitaxy. This IL is studied by reflection high-energy electron diffraction (RHEED), ion channeling, and x-ray diffraction. A correlation between the (1×2) RHEED pattern and the {111} CdTe stacking sequence is demonstrated, and is in favor of the surface Te dimerization hypothesis. Lattice location by ion channeling has revealed that incorporated Sm mainly occupies the octahedral site in the Te sublattice. A CdTe overlayer grown onto IL presents a remarkable feature, that is, a 90° rotation around the [001] direction with respect to the CdTe buffer. It was checked by ion channeling that the overlayer exhibited a bulklike crystallinity. Superlattices composed of many of these IL/CdTe basic periods have been grown at a temperature of 270 °C. The different experimental features are tentatively interpreted assuming the formation of an IL with the spinel structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354151
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  • 2
    Electronic Resource
    Electronic Resource
    Microscopic and macroscopic effects of electron irradiation on ferroelectric poly(vinylidene fluoride-TrFe) copolymers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4037-4044 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of electron irradiation on ferroelectric poly(vinylidene-trifluoroethylene) copolymers has been studied from both microscopic and macroscopic points of view. Microscopically, it is found by x-ray photoemission spectroscopy analysis and ultraviolet absorption that the irradiation damaging is mainly through dehydrofluorination and leads to double-bond production and crosslinking. On the other hand, dielectric permittivity, internal friction, x-ray diffraction, and differential scanning calorimetry experiments show that both the ferroelectric transition temperature Tc and the melting temperature Tm are lowered under irradiation. These various experimental features are consistently analyzed taking into account three main mechanisms resulting from the electron irradiation: (i) reduction of the crystallite mean size, (ii) changes in the internal pressure, and (iii) reduction of the dipolar energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349179
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  • 3
    Electronic Resource
    Electronic Resource
    Structural properties of undoped and doped cubic GaN grown on SiC(001) (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4983-4987 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transmission electron microscopy and x-ray diffraction measurements reveal the presence of stacking faults (SFs) in undoped cubic GaN thin layers. We demonstrate the importance of the defects in the interfacial region of the films by showing that the SFs act as nucleation sites for precipitates of residual impurities such as C and Si present in the GaN layers grown on SiC(001) substrates. We used the imaging secondary ion mass spectroscopy technique to locate these impurities. The systematic decrease of the SF density as a function of the layer thickness is explained by an annihilation mechanism. Finally, the effects of usual dopants on the structural properties of GaN layers are discussed. It is shown that Mg has a tendency to incorporate out of the Ga site by forming Mg precipitates for a concentration higher than 1019 cm−3 in contrast with the results found for heavily Si doped layers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456243
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  • 4
    Electronic Resource
    Electronic Resource
    Indium-modified growth kinetics of cubic and hexagonal GaN in molecular beam epitaxy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 4322-4325 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The kinetics changes in the growth of GaN induced by the presence of In segregated on the surface have been investigated in situ by using reflection high energy electron diffraction intensity oscillations. Two types of surfaces have been studied, namely, Ga-polar (0001) wurtzite, and (001) zinc blende. It has been found that In influenced both Ga and N surface kinetics, leading to a change in the growth rate associated with a change in the amount of Ga and N effectively available for the GaN growth. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371364
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  • 5
    Electronic Resource
    Electronic Resource
    Atomic-layer epitaxy of GaN quantum wells and quantum dots on (0001) AlN (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5498-5500 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that a dynamically stable Ga film is formed on (0001) AlN in a large range of Ga fluxes at a substrate temperature of 740 °C. This feature allows for atomic layer epitaxy (ALE) of GaN on AlN by alternate exposure to Ga and N flux. We show that, at a growth temperature of 740 °C, one ALE cycle leads to the formation of a two-dimensional GaN layer, whereas further cycles lead to the formation of GaN quantum dots following a Stranski–Krastanov growth mode. This behavior is confirmed by atomic force microscopy, transmission electron microscopy, and cathodoluminescence. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458049
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  • 6
    Electronic Resource
    Electronic Resource
    Low Schottky barrier height contacts to n-CdTe using rare-earth metals (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8541-8548 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-resistance contacts on n-type CdTe have been produced by molecular-beam epitaxy using metallic rare earths (europium, samarium, and neodymium). The metallic europium and neodymium epitaxy is achieved via an interfacial layer about 3 nm thick which results from the strong reactivity between the rare-earth metal and the tellurium semiconductor anion. For the two-dimensional growth of europium the interfacial layer is deliberately formed with samarium or neodymium, whereas for neodymium epitaxial growth the interfacial layer is formed with neodymium. Schottky barrier heights of the different heterostructures are determined by current–voltage characteristics and the specific contact resistance is measured using the transmission line model. The best results are obtained for neodymium/n-CdTe heterostructures with a specific contact resistance of 8×10−4 Ω cm2 for a doping level of 4×1017 cm−3. The Schottky barrier heights have been determined to be about 0.35±0.05 eV for the various rare-earth/n-CdTe heterostructures. The temperature and the doping level dependence of the current–voltage characteristics suggests furthermore that a dipolar layer is present at the interface. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362534
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  • 7
    Electronic Resource
    Electronic Resource
    Ohmic contacts on n-type CdTe and CdZnTe using coherently grown neodymium (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 514-516 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low resistance metallic contacts have been realized on n-type doped CdTe and CdZnTe layers grown by molecular beam epitaxy. The n-type doping of the layers was achieved using iodine or indium as a dopant. The metal/II–VI semiconductor heterostructures were realized with neodymium that was found to grow coherently on CdTe and CdZnTe substrates, with formation of a reacted compound at the interface. This interfacial layer is noted IL(Nd). The specific contact resistance, ρc, of the Nd/IL(Nd)/n-CdTe and Nd/IL(Nd)/n-CdZnTe heterostructures was measured using the transmission line model. The best result of 2.5×10−5 Ω cm2 is obtained for Nd/IL(Nd)/n-CdTe and for a doping level of about 6×1018 cm−3. An exponential increase of the ρc value is found when increasing zinc concentration in the CdZnTe alloys. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117771
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  • 8
    Electronic Resource
    Electronic Resource
    How to grow cubic GaN with low hexagonal phase content on (001) SiC by molecular beam epitaxy (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 2295-2300 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Molecular beam epitaxy (MBE) of cubic GaN on SiC films deposited by chemical vapor deposition on Si has been investigated by reflection high-energy electron diffraction, x-ray diffraction, photoluminescence, and micro-Raman spectroscopy. The wurtzite/zinc-blende ratio, indicative of the material quality, has been found to depend on both the initial substrate roughness and the N/metal ratio impinging on the surface. The results were consistently analyzed by assuming that the MBE growth of cubic GaN is mainly governed by the impinging active N flux, which directly determines the mean-free path of Ga adatoms. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368296
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  • 9
    Electronic Resource
    Electronic Resource
    Growth kinetics and optical properties of self-organized GaN quantum dots (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 7618-7624 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Self-organized GaN islands of nanometric scale were fabricated by controlling the Stranski–Krastanov growth mode of GaN deposited by molecular beam epitaxy on AlN. Evidence for ripening of dots under vacuum has been observed, resulting in changes in dot size distribution. We also show that in superlattice samples, consisting of multiple layers of GaN islands separated by AlN, the GaN islands are vertically correlated provided that the AlN layer thickness remains small enough. The luminescence peak of GaN dots is blueshifted with respect to bulk emission and its intensity does not vary with temperature, both effects demonstrating the strongly zero-dimensional character of these nanostructures.© 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367878
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of electron irradiation and annealing on ferroelectric vinylidene fluoride-trifluoroethylene copolymers (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 994-997 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that the Curie point of the ferroelectric vinylidene fluoride-trifluoroethylene copolymer can be shifted to the low temperatures by electron radiation. This effect was studied by in situ dielectric measurements as a function of the dose and of the irradiation temperature. An additional effect of the irradiation, in particular when performed at high temperature, was to noticeably decrease ε'. We also have studied annealing at temperatures around the melting point and shown that most of the irradiation damage was nonreversible and cumulative whereas part of it could be annealed. We have shown that it was apparently impossible to shift the Curie temperature lower than a limit temperature of the order of 0 °C. We discuss this effect and suggest the hypothesis of a competition with the glassy transition occuring in this temperature region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339685
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