Kevin S. Jones

Bio: Kevin S. Jones is an academic researcher from University of Florida. The author has contributed to research in topics: Ion implantation & Silicon. The author has an hindex of 38, co-authored 437 publications receiving 6226 citations. Previous affiliations of Kevin S. Jones include Bell Labs & University of Michigan.

A systematic analysis of defects in ion-implanted silicon

Abstract: A classification scheme for the different forms of implant-related damage which arise upon annealing consisting of five categories is presented. Category I damage is “subthreshold” damage or that which results prior to the formation of an amorphous layer. If the dose is increased sufficiently to result in the formation of an amorphous layer then the defects which form beyond the amorphous/crystalline (a/c) interface are classified as category II (“end of range”) damage. Category III defects are associated with the solid phase epitaxial growth of the amorphous layer. The most common forms of this damage are microtwins, hairpin dislocations and segregation related defects. It is possible to produce a buried amorphous layer upon implantation, If this occurs, then the defects which form when the two a/c interfaces meet are termed category IV (“clamshell”, “zipper”) defects. Finally, category V defects arise from exceeding the solid solubility of the implanted species in the substrate at the annealing temperature. These defects are most often precipitates or dislocation loops.

Three-Dimensional Reconstruction of Porous LSCF Cathodes

Abstract: Solid oxide fuel cells ! SOFCs" are efficient, environmentally friendly, and fuel-flexible electrochemical devices for the generation of electrical power and heat. 1 They consist of three basic layers: cathode, electrolyte, and anode. The cathode is a porous, conductive catalyst for the reduction of O2 and for the oxidation of fuel. Between the cathode and anode is the dense electrolyte. The circuit is completed via cathode and anode contacts to an external load. The basic chemical formula for the cathodic reduction reaction is 1 2 O2 +V o ·· +2 e! =O o x ! 1" Current SOFC performance is limited by cathode polarization, which increases with decreasing operational temperatures. 2,3 Cathode microstructure and morphology have a strong effect on this polarization. 2-4 In this initial study a dual-beam focused ion beam/scanning electron microscope ! FIB/SEM" was utilized to reconstruct an actual three-dimensional ! 3D" model of a La0.8Sr0.2Co0.2Fe0.8O3! ! ! LSCF" cathode and its interface with a dense yttrium-stabilized zirconia ! YSZ" electrolyte. This highresolution, 3D technique advances the understanding of the cathode microstructure’s effect on performance. The identification of critical microstructural properties such as surface area, tortuosity, and interfacial porosity may be correlated with the ionic, electronic, and catalytic processes for a better fundamental understanding of electrochemical performance. With this tool, SOFC material and microstructural design can be more effective in reducing cathodic polarization at lower operational temperatures. The semiconductor industry has used the FIB since the 1980s to deposit, etch, micromachine, and image specimens during different stages of circuit processing. 5,6 This technology was brought forward to reconstruct 3D, geometrically complex submicrometer structures. 7-11 With the advent of 3D modeling software, nanotomography utilizing the dual-beam FIB/SEM technique was used to quantify nanoceramic suspended powders. 10-12 This technique was applied to SOFC cermet anodes to quantify microstructural properties such as porosity, triple-phase-boundary ! TPB" length, and degree of anisotropy via tortuosity. 13 Such a technique has never before been applied to reconstruct a cathode and the cathode/ electrolyte interface.

In0.6Ga0.4As/GaAs quantum-dot infrared photodetector with operating temperature up to 260 K

Abstract: A high-sensitivity In0.6Ga0.4As/GaAs quantum-dot infrared photodetector (QDIP) with detection wave band in 6.7–11.5 μm and operating temperature up to 260 K under normal incident illumination has been demonstrated. The peak detection wavelength shifts from 7.6 to 8.4 μm when the temperature rises from 40 to 260 K. The background limited performance (BLIP) detectivity (DBLIP*) measured at Vb=−2.0 V, T=77 K, and λp=7.6 μm was found to be 1.1×1010 cm Hz1/2/W, with a corresponding responsivity of 0.22 A/W. The high operating temperature is attributed to the very low dark current and long carrier lifetime in the quantum dots of this device. The results show that this QDIP can operate at high temperature without using the large band gap material such as AlGaAs or InGaP as blocking barrier to reduce the device dark current.

CODATA Recommended Values of the Fundamental Physical Constants: 2006

Abstract: This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.

Lowering the Temperature of Solid Oxide Fuel Cells

Abstract: Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.

Gan : processing, defects, and devices

Abstract: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.