Anthony T. Fiory

Integrated Optical and Electronic Pressure Sensor

A pressure sensor that combines two principles of measurement into one integrated unit with optical and electronic parts is fabricated and tested. The sensing element for both integrated parts is an embossed silicon diaphragm that deflects under differential pressure. The optical part of the sensor is based on Fabry-Perot interferometry; the electronic part of the sensor is based on the piezoresistive effect in silicon. In the application of Fabry-Perot interferometry, the sensing element utilizes an optical cavity, where interference of multiple reflections changes with movement of the diaphragm caused by pressure. In the application of the piezoresistive effect, a change in the electrical resistivity of a sensor material is induced by mechanical stress in the diaphragm and detected by a Wheatstone bridge circuit. The advantages of introducing the embossed diaphragm in sensor fabrication and its benefits for integration are discussed. The existence of a nearly ideal Fabry-Perot interferometer in the optical part of the sensor is demonstrated experimentally. Noise characteristics of the Fabry-Perot part of the sensor are presented. The independently produced electronic output serves to establish the quiescence point (Q-point) of the output from the optical part of the sensor.

Theory of high-TC superconductivity: transition temperature

After reading over our published manuscript, we noticed that the discussion concerning the determination of σ for the ruthenate Ba2YRu0.9Cu0.1O6 in section 2.3.1 (3rd paragraph) is somewhat terse. Herein we provide an expanded analysis which better explains our estimate of γ (and thus σ) for this compound. All numbers, figures and conclusions remain unaltered. The ruthenate compounds A2YRu1-xCuxO6 (with A = Ba or Sr; x = 0.05–0.15) are double-perovskites containing no cuprate planes and with ν = μ = 1 [1] (reference [82] in the paper). The determination of γ follows from equation (2.5b), wherein rule 1b introduces the factor 1/2. In the lower limit, one expects a minimum of ~2 charges per Cu dopant, which are shared between two charge reservoirs of each layer type (AO and 1/2 (YRu1-xCuxO4)), producing a net factor of unity. Thus, for Ba2YRu0.9Cu0.1O6 (with TC0 ~ 30–40 K), we estimate γ = (1/2)(1) = 1/2, yielding σ = 0.05 as stated by equation (2.5c) in the paper. While one may expect an average effective charge state for Ru near +5, and that of Cu to be between +2 and +3 (post anneal) [2], the lower-limit estimation provided, which places the corresponding data point in figure 2 to the left of the line, appears sufficient to include the ruthenates with the other high-TC compounds found to follow equation (2.6) so far. Owing to the uncertainty in the experimental values for TC0, as well as the Ru and Cu valence states, however, this compound was excluded in the data analyses presented. Future research will attempt a more accurate determination of the charge per doped Cu, and thus σ. We would also like to point out a typographical correction in the definition of the corresponding ruthenate type II reservoir in the last column of table 1, which should read 1/2 (YRu0.9Cu0.1O4). An unrelated item is found in the fourth line of section 2.3.3, where Tb(O0.80F0.20)FeAs should read Tb(O0.80-yF0.20)FeAs. Additionally, reference [132] is now known and has the form: [132] Harshman D R and Fiory A T 2011 J. Phys.: Condens. Matter 23 315702 References [1] Parkinson N G, Hatton P D, Howard J A K, Ritter C, Chien F Z and Wu M-K 2003 J. Mater. Chem. 13 1468 [2] Rao S M, Wu M-K, Ren H C, Chen C L, Guo J-H, Hsu F C, Chen S Y, Chen Y Y, Chang C L and Liu H L 2011 in preparationThe superconducting transition temperatures of high-Tc compounds based on copper, iron, ruthenium and certain organic molecules are discovered to be dependent on bond lengths, ionic valences, and Coulomb coupling between electronic bands in adjacent, spatially separated layers [1]. Optimal transition temperature, denoted as T_c0, is given by the universal expression

Analytical study of thermal annealing behaviour of erbium emission in Er2O3-sol–gel silica films

k_BT_c0 = e^2 \Lambda / \ell\zeta

Rapid Thermal Processing of Silicon Wafers with Emissivity Patterns

;

Theory of High-Tc Superconductivity: Accurate Predictions of Tc

\ell

Room-temperature silicon band-edge photoluminescence enhanced by spin-coated sol–gel films

is the spacing between interacting charges within the layers, \zeta is the distance between interacting layers and \Lambda is a universal constant, equal to about twice the reduced electron Compton wavelength (suggesting that Compton scattering plays a role in pairing). Non-optimum compounds in which sample degradation is evident typically exhibit Tc < T_c0. For the 31+ optimum compounds tested, the theoretical and experimental T_c0 agree statistically to within +/- 1.4 K. The elemental high Tc building block comprises two adjacent and spatially separated charge layers; the factor e^2/\zeta arises from Coulomb forces between them. The theoretical charge structure representing a room-temperature superconductor is also presented.

The superconducting transition temperatures of Fe1+xSe1−y, Fe1+xSe1−yTey and (K/Rb/Cs)zFe2−xSe2

Room-temperature 1535 nm band photoluminescence in ~126 nm silica films (6 at% doping), produced by spin coating an Er2O3 and tetraethylorthosilicate sol–gel formulation on silicon substrates, was studied as a function of vacuum furnace annealing (500–1050 °C). Emission is strongly enhanced for annealing near 850 °C, which is shown by modelling the temperature dependence as arising from thermally activated removal of hydroxyl ions. Suitability of such a process for silicon-based applications is discussed.

Reply to “Comment on ‘Isotope effect in high- T c superconductors’ ”

Fabrication of devices and circuits on silicon wafers creates patterns in optical properties, particularly the thermal emissivity and absorptivity, that lead to temperature nonuniformity during rapid thermal processing (RTP) by infrared heating methods. The work reported in this paper compares the effect of emissivity test patterns on wafers heated by two RTP methods: (1) a steadystate furnace or (2) arrays of incandescent lamps. Method I was found to yield reduced temperature variability, attributable to smaller temperature differences between the wafer and heat source. The temperature was determined by monitoring test processes involving either the device side or the reverse side of the wafer. These include electrical activiation of implanted dopants after rapid thermal annealing (RTA) or growth of oxide films by rapid thermal oxidation (RTO). Temperature variation data are compared with a model of radiant heating of patterned wafers in RTP systems.

Comment on “Superconductivity in electron-doped layered TiNCl with variable interlayer coupling”

After reading over our published manuscript, we noticed that the discussion concerning the determination of σ for the ruthenate Ba2YRu0.9Cu0.1O6 in section 2.3.1 (3rd paragraph) is somewhat terse. Herein we provide an expanded analysis which better explains our estimate of γ (and thus σ) for this compound. All numbers, figures and conclusions remain unaltered. The ruthenate compounds A2YRu1-xCuxO6 (with A = Ba or Sr; x = 0.05–0.15) are double-perovskites containing no cuprate planes and with ν = μ = 1 [1] (reference [82] in the paper). The determination of γ follows from equation (2.5b), wherein rule 1b introduces the factor 1/2. In the lower limit, one expects a minimum of ~2 charges per Cu dopant, which are shared between two charge reservoirs of each layer type (AO and 1/2 (YRu1-xCuxO4)), producing a net factor of unity. Thus, for Ba2YRu0.9Cu0.1O6 (with TC0 ~ 30–40 K), we estimate γ = (1/2)(1) = 1/2, yielding σ = 0.05 as stated by equation (2.5c) in the paper. While one may expect an average effective charge state for Ru near +5, and that of Cu to be between +2 and +3 (post anneal) [2], the lower-limit estimation provided, which places the corresponding data point in figure 2 to the left of the line, appears sufficient to include the ruthenates with the other high-TC compounds found to follow equation (2.6) so far. Owing to the uncertainty in the experimental values for TC0, as well as the Ru and Cu valence states, however, this compound was excluded in the data analyses presented. Future research will attempt a more accurate determination of the charge per doped Cu, and thus σ. We would also like to point out a typographical correction in the definition of the corresponding ruthenate type II reservoir in the last column of table 1, which should read 1/2 (YRu0.9Cu0.1O4). An unrelated item is found in the fourth line of section 2.3.3, where Tb(O0.80F0.20)FeAs should read Tb(O0.80-yF0.20)FeAs. Additionally, reference [132] is now known and has the form: [132] Harshman D R and Fiory A T 2011 J. Phys.: Condens. Matter 23 315702 References [1] Parkinson N G, Hatton P D, Howard J A K, Ritter C, Chien F Z and Wu M-K 2003 J. Mater. Chem. 13 1468 [2] Rao S M, Wu M-K, Ren H C, Chen C L, Guo J-H, Hsu F C, Chen S Y, Chen Y Y, Chang C L and Liu H L 2011 in preparationThe superconducting transition temperatures of high-Tc compounds based on copper, iron, ruthenium and certain organic molecules are discovered to be dependent on bond lengths, ionic valences, and Coulomb coupling between electronic bands in adjacent, spatially separated layers [1]. Optimal transition temperature, denoted as T_c0, is given by the universal expression

Charge compensation and optimal stoichiometry in superconducting (Ca x La 1 − x )(Ba 1.75 − x La 0.25 + x )Cu 3 O y

k_BT_c0 = e^2 \Lambda / \ell\zeta