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Full-Text Articles in Physics

Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson Dec 2007

Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson

Physics Faculty Research

We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …


Scandium Oxide Thin Films And Their Optical Properties In The Extreme Ultraviolet, Guillermo Antonio Acosta Nov 2007

Scandium Oxide Thin Films And Their Optical Properties In The Extreme Ultraviolet, Guillermo Antonio Acosta

Theses and Dissertations

This study reports on the physical and optical characterization of scandium oxide thin films. Thin films of scandium oxide, 20-40 nm thick, were deposited on silicon wafers, quartz slides, and silicon photodiodes by reactively sputtering scandium in an oxygen environment. These samples were characterized using ellipsometry, high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis. A 28.46 nm thick scandium oxide thin film was measured in the Extreme Ultraviolet (EUV) from 2.7 to 50 nm (459.3 to 24.8 eV) using synchrotron radiation at the Advanced Light Source Beamline 6.3.2 at the Lawrence Berkeley National Laboratory. In …


Piezomagnetism In Epitaxial Cr2o3 Thin Films And Spintronic Applications, Sarbeswar Sahoo, Christian Binek Mar 2007

Piezomagnetism In Epitaxial Cr2o3 Thin Films And Spintronic Applications, Sarbeswar Sahoo, Christian Binek

Christian Binek Publications

Stress-induced perturbation of the antiferromagnetic long-range order in epitaxially grown Cr2O3 thin films gives rise to pronounced piezomagnetism and a significant reduction of the antiferromagnetic ordering temperature. The temperature dependence of the piezomagnetic moment measured by superconducting quantum interference device magnetometry reveals a power law behaviour with a critical exponent 2B=0.66 in accordance with the Ising anisotropy of a three-dimensional system. The observed shift of the Neel temperature allows estimating the internal lateral stress which is in excellent agreement with an independent estimate based on the elastic properties of Cr2O3 and the lattice mismatch at the interface between the sapphire …


Role Of Sn In The Density Of Defect States In A-Se_{0.75}Te_{0.25} And A-Se_{0.85}Te_{0.15}Thin Films, N. Sharma, Santosh Kumar Jan 2007

Role Of Sn In The Density Of Defect States In A-Se_{0.75}Te_{0.25} And A-Se_{0.85}Te_{0.15}Thin Films, N. Sharma, Santosh Kumar

Turkish Journal of Physics

In this paper we report the effect of Sn incorporation in the density of defect states of two binary Se-Te glassy systems, comparing the properties of a-Se_{0.75}Te_{0.25}, a-Se_{0.85}Te_{0.15} and a-Se_{0.75}Te_{0.15}Sn_{0.10} glassy alloys. Properties of d.c. conductivity at high electric fields in vacuum were examined; and current-voltage (I-V) characteristics have been measured at various fixed temperatures. Ohmic behavior is observed at low electric fields; while at high electric fields (E \sim 10^4 V/cm), non-ohmic behavior is observed. An analysis of the experimental data confirms the presence of space charge limited conduction (SCLC) in the studied glassy materials. Density of defect states …


Opto-Electrical Properties Of Copper-Indium-Selenium Thin Films, S. F. Shaukat, S. A. Khan, Robina Farooq Jan 2007

Opto-Electrical Properties Of Copper-Indium-Selenium Thin Films, S. F. Shaukat, S. A. Khan, Robina Farooq

Turkish Journal of Physics

Copper-Indium-Selenium (CIS) thin films have been characterised using various experimental techniques. These compounds are extensively used in solar cell technology as absorber layers due to their exciting characteristics. Optical transmission measurements on different compositions of CIS films are observed and the absorption coefficient is determined. The Van der Pauw technique is used to divulge the electrical characteristics of these films. The electrical conductivity is found relatively high for the films annealed in vacuum but decreases for films synthesised optimally. It is observed that p-type films have higher conductivity than n-type films. The grain size, composition, structure and the spacing of …


Preparation And Study Of The Structural, Optical And Electrical Properties Of Cu(In,Ga)Se_2 Thin Films, Athar Javed Jan 2007

Preparation And Study Of The Structural, Optical And Electrical Properties Of Cu(In,Ga)Se_2 Thin Films, Athar Javed

Turkish Journal of Physics

Thin film samples of Cu(In,Ga)Se_2 (CIGS) were prepared at room temperature by physical vapor deposition (PVD) technique using resistive heating method onto soda lime glass substrates. Deposition conditions were same for all the samples. The prepared samples were annealed in vacuum at temperature of 200 °C for 5, 10, 15, 30 and 60 minutes and were characterized structurally, optically and electrically. The structural analysis indicate the partial formation of quaternary CIGS compounds for the samples which were annealed in vacuum at 200 °C for 30 and 60 minutes. XRD analysis indicate that there is a continuous growth and improvement in …