Search results for "abs"
showing 10 items of 6504 documents
Description of intermodulation generation of nonlinear responses beyond the validity of the power series expansion
2021
Weakly nonlinear responses are commonly described by a power series expansion. However, intermodulation distortion products that cannot be described by a power series have been observed in a variety of physical systems. As the power series description is only applicable within its radius of convergence, we choose an alternative approach based on Fourier coefficients to describe intermodulation levels beyond the convergence of the power series. The description over a wide power range allows us to make a decision about models and to determine previously inaccessible model parameters. We apply the approach to data obtained from the characterization of the nonlinear dielectric susceptibility of…
Influence of “Productive” Impurities (Cd, Na, O) on the Properties of the Cu 2 ZnSnS 4 Absorber of Model Solar Cells
2021
The research has been supported by grant of the Ministry of Education and Science of the Republic of Kazakhstan AP09562784. The authors (D. Sergeyev) acknowledges the provision of SCAPS-1D software by Prof. Marc Burgelman. The research of A.I. Popov has been supported by the Institute of Solid State Physics (ISSP), University of Latvia (UL). ISSP UL as the Centre of Excellence is supported through the Framework Program for Euro-pean Universities Union Horizon 2020, H2020-WIDESPREAD-01–2016–2017-TeamingPhase2 under Grant Agreement No. 739508, CAMART2 project.
Enhanced acoustic pressure sensors based on coherent perfect absorber-laser effect
2021
Lasing is a well-established field in optics with several applications. Yet, having lasing or huge amplification in other wave systems remains an elusive goal. Here, we utilize the concept of coherent perfect absorber-laser to realize an acoustic analog of laser with a proven amplification of more than 10 4 in terms of the scattered acoustic signal at a frequency of a few kHz. The obtained acoustic laser (or the coherent perfect absorber-laser) is shown to possess extremely high sensitivity and figure of merit with regard to ultra-small variations of the pressure (density and compressibility) and suggests its evident potential to build future acoustic pressure devices such as precise sensor…
Silicon dosimeters based on Floating Gate Sensor: design, implementation and characterization
2020
A rad-hard monolithic dosimeter has been implemented and characterized in a standard 180 nm CMOS technology. The radiation sensor (C-sensor) is based on a Floating Gate (FG) MOS discharge principle. The output current is processed by a current-to-voltage (I/V) interface and then converted by a 5-bit flash ADC. The dosimeter is re-usable (FG can be recharged) and can detect a dose up to 1krad (Si) with a resolution of 30rad (Si) typical over temperature 0 to 85°C range. The ADC allows easy further signal processing for calibration and averaging, etc. The power consumption of C-sensor plus I/V interface is < 2mW from a 5 V power supply. The overall layout area is less than 0.25mm2. The Rad…
Refractive index controlled by film morphology and free carrier density in undoped ZnO through sol-pH variation
2018
Abstract Zinc oxide thin films, prepared by the sol-gel process, were deposited on glass substrate using spin coating technique. The sol-pH effect on the optical parameters was studied for alkaline sol. The surface roughness was investigated by atomic force microscopy (AFM) and varied from 20 to 40 nm. The optical transmission measurements were carried out to evaluate the behavior of the extinction coefficient and the refractive index. An exponential decay of the refractive index ‘n’ as a function of wavelength was observed. The refractive index increases slightly when the pH increases to pH = 9.5 where it reaches its maximum. Beyond this value, it decreases sharply. This behavior has been …
Spectroscopic study of the electric field induced valence change of Fe-defect centers in SrTiO(3)
2011
The electrochemical changes induced by an electric field in Fe-doped SrTiO(3) have been investigated by X-ray absorption spectroscopy (XANES and EXAFS), electron paramagnetic resonance (EPR) and Raman spectroscopy. A detailed study of the Fe dopant in the regions around the anode and cathode reveals new insights into the local structure and valence state of Fe in SrTiO(3) single crystals. The ab initio full multiple-scattering XANES calculations give an evidence of the oxygen vacancy presence in the first coordination shell of iron. Differences in the length and disorder of the Fe-O bonds as extracted from EXAFS are correlated to the unequivocal identification of the defect type by compleme…
Positron trapping defects in free-volume investigation of Ge–Ga–S–CsCl glasses
2016
Abstract Evolution of free-volume positron trapping defects caused by crystallization process in (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 15 chalcogenide-chalcohalide glasses was studied by positron annihilation lifetime technique. It is established that CsCl additives in Ge–Ga–S glassy matrix transform defect-related component spectra, indicating that the agglomeration of free-volume voids occurs in initial and crystallized (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 10 glasses. Void fragmentation in (80GeS 2 –20Ga 2 S 3 ) 85 (СsCl) 15 glass can be associated with loosing of their inner structure. Full crystallization in each of these glasses corresponds to the formation of defe…
Synergistic effect of fiber content and length on mechanical and water absorption behaviors of Phoenix sp. fiber-reinforced epoxy composites
2016
Phoenix sp. fiber-reinforced epoxy composites have been manufactured using compression molding technique. The effect of reinforcement volume content (0%, 10%, 20%, 30%, 40%, and 50%) and size (300 µm particles, 10 mm, 20 mm, and 30 mm fibers) on quasi-static and dynamic mechanical properties was investigated. Moreover, the water absorption properties of composites were analyzed at different environmental conditions (10℃, 30℃, and 60℃). For each reinforcement size, composites loaded with 40% in volume show highest tensile and flexural properties. Furthermore, composites with 300 µm particles present the best impact properties and the lowest water absorption, regardless of the environmental …
Simulation of IQE tuning of individual cells for DC-balancing multijunction tandem cells
2016
In the present work, the performance of stacks of cells connected in series is examined at different levels of internal quantum efficiency (IQE). Incident photons, generated by employing the ASTM G173-03 data set, are accounted for individually as they interact with the stack of cells. The efficiencies of the devices studied are dependent upon the DC balance throughout the stack of cells. It is demonstrated that reducing the internal quantum efficiency of upper cells can lead to a better DC balance and thereby higher efficiency.
Simulations of the effect of the contact energy levels on a simple model of a hot carrier cell
2016
In the present work, the performance of a simplified model of a hot carrier cell is examined at different energy levels of carrier collection. Incident photons, Monte Carlo generated by employing the ASTM G173-03 data set, are accounted for individually as they interact with the cell. It is assumed that the carriers can be collected ultra-fast, thus avoiding considering hot carrier thermalisation effects. Although the model is preliminary and lacking some mechanisms of hot carrier cells, it has been demonstrated that the present approach to modelling hot carrier solar cells can be developed into fully working models. Some effects of the absorption energy levels in the valence band have been…