Author
Jensen James D
Other affiliations: United States Department of the Navy
Bio: Jensen James D is an academic researcher from Silver Spring Networks. The author has contributed to research in topics: Chalcogenide & Cadmium sulfide. The author has an hindex of 4, co-authored 5 publications receiving 438 citations. Previous affiliations of Jensen James D include United States Department of the Navy.
Papers
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TL;DR: In this article, single-crystal films of PbS, pbTe, PbSe, and SnTe have been grown on heated alkali-halide substrates.
Abstract: Single-crystal films of PbS, PbTe, PbSe, and SnTe have been grown on heated alkali-halide substrates. The temperature dependence of the mobility, Hall coefficient, and resistivity between 77\ifmmode^\circ\else\textdegree\fi{}K and 300\ifmmode^\circ\else\textdegree\fi{}K and the dependence of the magnetoresistance upon sample orientation and magnetic field strength at 77\ifmmode^\circ\else\textdegree\fi{}K have been studied. Analysis of the refractive indices, measured interferometrically in the 2.0- to 15.0-\ensuremath{\mu} region, has yielded optical dielectric constants and the direct energy gaps as functions of temperature. These studies indicate that the single-crystal films have electrical and optical properties comparable to those found in bulk material. Discussions of film formation and strain phenomena are presented and compared with the experimental results. Some of the limitations of these materials are discussed with particular emphasis on the role of structure of the films on the electrical properties.
457 citations
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21 Nov 1978
TL;DR: The process of coating epitaxial films of lead chalcogenide materials with As2S3 to insulate the films from the effects of oxygen upon exposure to air is described in this article.
Abstract: The process of coating epitaxial films of lead chalcogenide materials with As2S3 to insulate the films from the effects of oxygen upon exposure to air
10 citations
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27 Dec 1977TL;DR: In this article, a variable temperature method for the preparation of single and multiple epitaxial layers of single-phase (e.g., face-centered cubic), ternary lead chalcogenide alloys was proposed.
Abstract: A variable temperature method for the preparation of single and multiple epitaxial layers of single-phase (e.g., face-centered cubic), ternary lead chalcogenide alloys (e.g., lead cadmium sulfide, [Pbl-wCdwla[S]l-a wherein ".omega." varied between zero and fifteen hundredths, inclusive, and a=0.55 +0.003), deposited upon substrates of barium fluoride, BaF2, maintained in near thermodynamic equilibrium with concurrently sublimated lead alloy and chalcogenide sources. During pre-paration, the temperature of the substrate is varied, thereby providing An epilayer with graded composition and pre-determined electrical and optical properties along the direction of growth.This growth technique can be used to produce infrared lenses, narrowband detectors, and double heterojunction lasers.
7 citations
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04 Aug 1981
TL;DR: A variable temperature method for the preparation of single and multiple epitaxial layers of single-phase (e.g., face-centered cubic), ternary lead chalcogenide alloys was proposed in this paper.
Abstract: A variable temperature method for the preparation of single and multiple epitaxial layers of single-phase (eg, face-centered cubic), ternary lead chalcogenide alloys (eg, lead cadmium sulfide, [Pb1-wCdw]a[S]1-a wherein w varies between zero and fifteen hundredths, inclusive, and a=0500+/-0003), deposited upon substrates of barium fluoride, BaF2, maintained in near thermodynamic equilibrium with concurrently sublimated lead alloy and chalcogenide sources During preparation, the temperature of the substrate is varied, thereby providing an epilayer with graded composition and predetermined electrical and optical properties along the direction of growth This growth technique can be used to produce infrared lenses, narrowband detectors, and double heterojunction lasers
4 citations
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24 Sep 2002Abstract: CRYSTALLINE MATERIALS Introduction Physical Properties Optical Properties Mechanical Properties Thermal Properties Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties GLASSES Introduction Commercial Optical Glasses Specialty Optical Glasses Fused Silica Fluoride Glasses Chalcogenide Glasses Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties Special Glasses POLYMERIC MATERIALS Optical Plastics Index of Refraction Nonlinear Optical Properties Thermal Properties Engineering Data METALS Physical Properties of Selected Metals Optical Properties Mechanical Properties Thermal Properties Mirror Substrate Materials LIQUIDS Introduction Water Physical Properties of Selected Liquids Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Commercial Optical Liquids GASES Introduction Physical Properties of Selected Gases Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Atomic Resonance Filters APPENDICES Safe Handling of Optical Materials Abbreviations, Acronyms, and Mineralogical or Common Names for Optical Materials Abbreviations for Methods of Preparing Optical Materials and Thin Films Fundamental Physical Constants Units and Conversion Factors
1,262 citations
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TL;DR: It is shown that Sn self-compensation can effectively reduce the Sn vacancies and decrease the hole carrier density, and alloying with Cd atoms enables a form of valence band engineering that improves the high-temperature thermoelectric performance.
Abstract: SnTe is a potentially attractive thermoelectric because it is the lead-free rock-salt analogue of PbTe. However, SnTe is a poor thermoelectric material because of its high hole concentration arising from inherent Sn vacancies in the lattice and its very high electrical and thermal conductivity. In this study, we demonstrate that SnTe-based materials can be controlled to become excellent thermoelectrics for power generation via the successful application of several key concepts that obviate the well-known disadvantages of SnTe. First, we show that Sn self-compensation can effectively reduce the Sn vacancies and decrease the hole carrier density. For example, a 3 mol % self-compensation of Sn results in a 50% improvement in the figure of merit ZT. In addition, we reveal that Cd, nominally isoelectronic with Sn, favorably impacts the electronic band structure by (a) diminishing the energy separation between the light-hole and heavy-hole valence bands in the material, leading to an enhanced Seebeck coefficien...
510 citations
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TL;DR: In this article, a thermoelectric generator is used to directly convert heat into electricity, which holds great promise for tackling the ever-increasing energy sustainability issue in the future.
Abstract: Thermoelectric generators, capable of directly converting heat into electricity, hold great promise for tackling the ever-increasing energy sustainability issue. The thermoelectric energy conversio...
351 citations
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TL;DR: In this paper, the effects of optimizing the thermoelectric figure of merit, zT, by controlling the doping level were investigated. But the effect of the doping on the performance of PbTe was not considered.
Abstract: Taking La- and I-doped PbTe as an example, the current work shows the effects of optimizing the thermoelectric figure of merit, zT, by controlling the doping level. The high doping effectiveness allows the carrier concentration to be precisely designed and prepared to control the Fermi level. In addition to the Fermi energy tuning, La-doping modifies the conduction band, leading to an increase in the density of states effective mass that is confirmed by transport, infrared reflectance and hard X-ray photoelectron spectroscopy measurements. Taking such a band structure modification effect into account, the electrical transport properties can then be well-described by a self-consistent single non-parabolic Kane band model that yields an approximate (m*T)^(1.5) dependence of the optimal carrier concentration for a peak power factor in both doping cases. Such a simple temperature dependence also provides an effective approximation of carrier concentration for a peak zT and helps to explain, the effects of other strategies such as lowering the lattice thermal conductivity by nanostructuring or alloying in n-PbTe, which demonstrates a practical guide for fully optimizing thermoelectric materials in the entire temperature range. The principles used here should be equally applicable to other thermoelectric materials.
341 citations
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TL;DR: In this paper, the fundamental material properties of Pb1−xSnxTe, PbS 1−xSex and Pb 1−XSnxSe are reviewed.
Abstract: The fundamental material properties of Pb1−xSnxTe, PbS1−xSex and Pb1−xSnxSe are reviewed. Expressions for the temperature and compositional dependences of the band parameters and dielectric constants based on recently published data are presented. As far as device technology is concerned, crystal growth techniques and diode fabrication procedures which are in use today are reviewed and compared. A comprehensive summary of laser properties like threshold current density, output power, efficiency, maximum operating temperature and tuning range of different diode structures are presented. Application related aspects such as long term stability are treated. Recent progress in laser theory is applied to explain experimentali
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vs.T curves. The various laser applications are reviewed briefly. A new technique for monitoring gas concentrations using pulsed lasers and an integral method for signal processing is discussed and compared with the differential absorption, derivative spectroscopy. A long-path trace-gas monitoring system incorporating this new technique is presented.
337 citations