General relativistic spinning fluids with a modified projection tensor

An energy-momentum tensor for general relativistic spinning fluids compatible with Tulczyjew-type supplementary condition is derived from the variation of a general Lagrangian with unspecified explicit form. This tensor is the sum of a term containing the Belinfante-Rosenfeld tensor and a modified perfect-fluid energy-momentum tensor in which the four-velocity is replaced by a unit four-vector in the direction of fluid momentum. The equations of motion are obtained and it is shown that they admit a Friedmann-Robertson-Walker space-time as a solution.Comment: Submitted to General Relativity and Gravitatio

Mechanochemically Synthesized CIGS Nanocrystalline Powder for Solar Cell Application

Copper Indium Gallium Diselenide (CIGS) is a compound semiconductor material from the group of I-III-VI. The material is a solid solution of copper, indium and selenium (CIS) and copper, gallium and selenium with an empirical formula of CuIn(1 – x)GaxSe2, where 0 x 1. CIGS has an exceptionally high absorption coefficient of more than 105 cm – 1 for 1.5 eV. Solar cells prepared from absorber layers of CIGS materials have shown an efficiency higher than 20 %. CuIn(1 – x)GaxSe2 (x 0.3) nanocrystalline compound was mechanochemically synthesized by high-energy milling in a planetary ball mill. The phase identification and crystallite size of milled powders at different time intervals were carried out by X-ray diffraction (XRD). The XRD analysis indicates chalcopyrite structure and the crystallite size of about 10 nm of high-energy milled CIGS powder after two and half hours of milling. An attempt for preparing the thin film from CIGS nanocrystalline powder was carried out using the flash evaporation technique. Scanning electron microscopy (SEM) reveals uniform distribution of CIGS particles in thin film. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3100

Simulation of CIGS thin film solar cells using AMPS-1D

The solar cell structure based on copper indium gallium diselenide (CIGS) as the absorber layer, cadmium sulfide (CdS) as a buffer layer un-doped (i) and Aluminium (Al) doped zinc oxide (ZnO) as a window layer was simulated using the one dimensional simulation program called analysis of microelectronic and photonic structures (AMPS-1D). In the simulation, the thickness of CIGS layer was varied from 300 to 3000 nm. The rest of layer’s thicknesses were kept constant, viz. 60 nm for CdS, and 80 nm and 500 nm for i- and Al-ZnO, respectively. By varying thickness of CIGS layer the simulated device performance was demonstrate in the form of current-voltage (I-V) characteristics and quantum efficiency (QE). When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2209

Magnetron sputtered Al-ZnO Thin films for photovoltaic applications

The optimization process of the RF magnetron sputtered Al - doped ZnO (AZO) thin films was carried out by studying its structural, optical, electrical, and morphological properties at different RF power and different working pressures for its use as a front-contact for the copper indium diselenide (CIS) based thin film solar cell. The structural study suggests that the preferred orientation of grains along the ( 002) plane having a hexagonal structure of the grains. The optical and electrical properties suggest that the films show an average transmission of 85 % and a resistivity of the order of 10-4 Wcm. The morphology analysis suggests the formation of packed grains having a homogeneous surface. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2210

Dynamical Chern-Simons modified gravity, Godel Universe and variable cosmological constant

We study the condition for the consistency of the G\"{o}del metric with the dynamical Chern-Simons modified gravity. It turns out to be that this compatibility can be achieved only if the cosmological constant is variable in the space.Comment: 8 pages, references adde

Molybdenum back-contact optimization for CIGS thin film solar cell

Molybdenum (Mo) thin films are most widely used as an ohmic back-contact in the copper indium diselenide (CIS) and its alloy copper indium gallium diselenide (CIGS) based thin film solar cell. Radio frequency (RF) magnetron sputtering system used to deposit Mo thin films on soda lime glass substrate. The deposition was carried out using argon (Ar) gas at different Ar controlled (working) pressures (1 mTorr to 10 mTorr) and at different RF powers (60 W to 100 W). The influence of both the working pressure and the RF power on the Mo thin films was studied by investigating its structural, morphological, electrical, and optical measurements. The results reveal that a stress-free, low-sheet-resistance (~1 W/), and reflecting (~ 55 %) Mo thin film was observed at 1 mTorr working pressure and 100 W RF power. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2211

Amplitude and phase representation of quantum invariants for the time dependent harmonic oscillator

The correspondence between classical and quantum invariants is established. The Ermakov Lewis quantum invariant of the time dependent harmonic oscillator is translated from the coordinate and momentum operators into amplitude and phase operators. In doing so, Turski's phase operator as well as Susskind-Glogower operators are generalized to the time dependent harmonic oscillator case. A quantum derivation of the Manley-Rowe relations is shown as an example

Laser scribing optimization of RF magnetron sputtered molybdenum thin films

The optimization process of laser scribing of back contacts is carried out by varying different parameters of laser and thickness of Molybdenum (Mo) thin-films. Mo thin films were deposited by RF magnetron sputtering on the organically cleaned soda lime glass substrate. The thickness of Mo was in the range of 60 nm to 800 nm. For the scribing process the laser power and the laser pulse frequency were varied. Different thickness of Mo shows the different scribe behavior. The optimized process provides a successful isolative laser scribing, having a minimum scribe line width, of Mo layer on glass substrate without any presence of walls, ridges, or collars in scribed areas. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/929

Effect of Rapid Thermal Annealing of CIGS Thin Film as an Absorber Layer

The influence of rapid post-deposition thermal annealing (500 °C for 2 minutes) on the CIGS thin films of different thicknesses (0.4 to 1.0 m) has been investigated. The deposition of CIGS is carried out using the flash evaporation at the substrate temperature of 250 °C. The as-grown and annealed CIGS is characterized by XRD, SEM, EDS, TEM, optical transmission, reflection, and electrical measurements. Lowering the thickness of CIGS absorber shows the remarkable influence on crystal structure, surface morphology, and composition of the overall film. Further improvement was observed by the rapid annealing process. Cu-rich composition was observed for annealed CIGS thin film having a thickness below 0.6 μm, while for 1.0 m thickness the composition is slightly Cu-poor and the compactly packed faceted grains observed. Optical band gap near to 1.05 eV and the electrical resistivity in the order of 104 Ωcm shows its future use as an absorber layer for CIGS solar cell. Furthermore, an attempt of making CIGS / CdS hetero-structure shows ideal behavior of the Schottky hetero-structure with the ideality factor of 1.5. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3100

Impact of annealing on CuInSe2 thin films and its Schottky interface

The room temperature current–voltage (I-V) characteristics of the Al/p-CuInSe2 Schottky Diodes fabricated on thermally evaporated CIS thin films, before and after annealing, were studied. Prior to their diode formation, the undertaken CIS thin films were compared on the basis of structural, morphological and electrical investigations. Wherein, annealed films showed an increase in the grain size and carrier concentration values while decrease in resistivity. I-V analysis of the Schottky diodes depicted decrease in the barrier heights and increase in ideality factors of those formed on annealed films. The diodes, thus, indicated the existence of barrier inhomogenity at the M-S interface. The annealed Schottky diodes also demonstrated better ideality factor values with increased thickness of CIS layer. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2792