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Optical description of HfO2/Al/HfO2 multilayer thin film devices
M. Ramzan,A.M. Rana,E. Ahmed,A.S. Bhatti,M. Hafeez,A. Ali,M.Y. Nadeem 한국물리학회 2014 Current Applied Physics Vol.14 No.12
A three-layer system of dielectric/metal/dielectric (D/M/D) has been prepared on Marienfeld commercial glass substrates with Metal ¼ Al, and Dielectric ¼ HfO2 for energy efficient windows applications. Subsequently, HfO2/Al/HfO2 multilayers have been deposited with 10 nm each HfO2 layer and 5 nm thick Al layer using electron beam evaporation. The microstructural characteristics of D/M/D thin films have been investigated using X-ray diffraction (XRD) and atomic force microscopy (AFM). Present results indicate the formation of HfO2 weak polycrystals embedded in the disordered lattice. AFM data reveals quite a smooth surface involving a structure of slightly elongated grains with almost Gaussian size distribution with mean grain size in the range from 7 to 23 nm. Regarding optical properties, maximum transmittance of the D/M/D structure is noticed to occur in the UV-region, whereas reflectance rises to ~60% in the visible to near infrared (NIR)-regions. To optimize the performance of these D/M/D devices, computer calculations have been performed by varying either the thickness of both HfO2 layers and/or thickness of metallic Al layer. A satisfactory agreement between theoretical and experimental spectra is noticed. Such D/M/D structures can be useful in heat mirror applications involving energy efficient windows etc.
Nanomechanical Logic Elements Based on Coupled Nanopillars
S. H. Kim,S. J. Hong,A. S. Rana,김현석 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.7
We demonstrate the possibility of using coupled nanopillars as nanomechanical logic elements byregulating the flow of electric current between the nanopillars and the source and drain electrodes. The nanopillar, which is fabricated from a silicon-on-insulator (SOI) wafer and is located betweentwo facing electrodes, oscillates with frequencies in the radiofrequency range of 10 - 1000 MHz. Electrons are transported between the nanopillar and the electrodes via an island-like gold layerthermally deposited on the top of the nanopillar in response to externally applied ac and dc biases. Nanomechanical logic gates are designed using the coupled nanopillars and a switched-capacitormodel. With this configuration, several logic gates, such as an inverter and NAND, NOR, andXOR gates, can be effectively implemented.
Shahmirzadi, Solaleh,Sharaf, Rana A.,Saadat, Sarang,Moore, William S.,Geha, Hassem,Tamimi, Dania,Kocasarac, Husniye Demirturk Korean Academy of Oral and Maxillofacial Radiology 2021 Imaging Science in Dentistry Vol.51 No.1
Purpose: The aim of this study was to assess artifacts generated in cone-beam computed tomography (CBCT) of 3 types of dental implants using 3 metal artifact reduction (MAR) algorithm conditions (pre-acquisition MAR, post-acquisition MAR, and no MAR), and 2 peak kilovoltage (kVp) settings. Materials and Methods: Titanium-zirconium, titanium, and zirconium alloy implants were placed in a dry mandible. CBCT images were acquired using 84 and 90 kVp and at normal resolution for all 3 MAR conditions. The images were analyzed using ImageJ software (National Institutes of Health, Bethesda, MD) to calculate the intensity of artifacts for each combination of material and settings. A 3-factor analysis of variance model with up to 3-way interactions was used to determine whether there was a statistically significant difference in the mean intensity of artifacts associated with each factor. Results: The analysis of all 3 MAR conditions showed that using no MAR resulted in substantially more severe artifacts than either of the 2 MAR algorithms for the 3 implant materials; however, there were no significant differences between pre- and post-acquisition MAR. The 90 kVp setting generated less intense artifacts on average than the 84 kVp setting. The titanium-zirconium alloy generated significantly less intense artifacts than zirconium. Titanium generated artifacts at an intermediate level relative to the other 2 implant materials, but was not statistically significantly different from either. Conclusion: This in vitro study suggests that artifacts can be minimized by using a titanium-zirconium alloy at the 90 kVp setting, with either MAR setting.
M. Ismail,A.M. Rana,S.-U. Nisa,F. Hussain,M. Imran,K. Mahmood,I. Talib,E. Ahmed,D.H. Bao 한국물리학회 2017 Current Applied Physics Vol.17 No.10
Bilayer CeO2/TiO2 films with high-k dielectric property were prepared by rf magnetron sputtering technique at room temperature. Effect of annealing treatment on resistive switching (RS) properties of bilayer CeO2/TiO2 films in O2 ambient at different temperature in the range of 350e550 C was investigated. Our results revealed that the bilayer films had good interfacial property at 500 C and this annealing temperature is optimum for different RS characteristics. Results showed that bilayer CeO2/TiO2 film perform better uniformity and reliability in resistive switching at intermediate temperature (i.e. 450 C and 500 C) instead of low and high annealing temperature (i.e. 350 C and 550 C) at which it exhibits poor crystalline structure with more amorphous background. Less Gibbs free energy of TiO2 as compared to CeO2 results in an easier re-oxidation of the filament through the oxygen exchange with TaN electrode. However, the excellent endurance property (>2500 cycles), data retentions (105 s) and good cycle-to-cycle uniformity is observed only in 500 C annealed devices. The plots of cumulative probability, essential memory parameter, show a good distribution of Set/Reset voltage.