The future of the industry development depends greatly on the permanently ensured energy needs and can be achieved only through the use of a variety of sustainable energy sources where the solar energy, which gains its optimal exploitation directly by linking it to the properties of solar cells and in particular to the crystallographic quality of the used semiconductor substrates, is one of them. Many growth processes are used to obtain a high quality of semiconductor formation and deposition, among them the DC sputtering. In this work, based on the Monte-Carlo method, a 3D DC sputtering simulation of the CZTS {\mathrm{CZTS}} , Si {\mathrm{Si}} and CIGS {\mathrm{CIGS}} semiconductors thin film formation is proposed by considering Argon as vacuum chamber bombardment gas. We extrapolate firstly the best sputtering yield possible of the semiconductors CZTS {\mathrm{CZTS}} and Silicon represented by their chemical formulas Cu 2 ZnSnS 4 {\mathrm{Cu}_{2}\mathrm{Zn}\mathrm{Sn}\mathrm{S}_{4}} and Si {\mathrm{Si}} , respectively, by the application of different energies and incidence angles. From the obtained results, firstly we deduce that the best sputtering angle is 85 ∘ {85^{\circ}} ; in the same time, CZTS {\mathrm{CZTS}} is more efficient comparing to the Si {\mathrm{Si}} . Secondly, with the application of this angle ( 85 ∘ {85^{\circ}} ) in the sputtering process for the CZTS {\mathrm{CZTS}} ( Cu 2 ZnSnS 4 {\mathrm{Cu}_{2}\mathrm{Zn}\mathrm{Sn}\mathrm{S}_{4}} ) and CIGS {\mathrm{CIGS}} represented by its chemical formula CuIn x Ga ( 1 - x ) Se 2 {\mathrm{Cu}\mathrm{In}_{x}\mathrm{Ga}_{(1-x)}\mathrm{Se}_{2}} , and the variation of the bombardment energy in order to find the total ejected atoms from each element of these two materials, we deduce that the sulfide ( S 4 {\mathrm{S}_{4}} ) and selenide ( Se 2 {\mathrm{Se}_{2}} ) elements give the majority of the sputtering yield amount obtained.
Designing thin film solar cells with high and stable output performance under different operating points remains a large area of research. In the context of Chalcopyrite-based solar cells (CuInxGa(1-x)Se2) where the buffer layer is CdS, great progress has been made but research is still underway to optimize their performance. Besides the environmental concerns and limiting factors of CdS material, the use or combination of new materials like ZnS, ZnSe and WS2 as a buffer layer is solicited. Due to these attracted optical and crystallographic properties, Tungsten Disulfide: WS2 is solicited during the last years. Through numerical simulation, we investigate in this work the dc parameters of CuInxGa(1-x)Se2/WS2 solar cell with reduced buffer layer thickness of 30 nm. Considering the presence of neutral and divalent defects in the absorber layer, simulations are performed under the impact of temperature, concentration of charge carriers in WS2 layer and light spectrum change. The divalent defects taken into account are: double donors / acceptors and amphoteric having a Gaussian distribution. For more calculation precision and in order to obtain the desired performance of the solar cell, the impact of series and shunt resistors is also considered. In comparison with results reported in previous works, carried out on the CuInxGa(1-x) Se2/WS2 solar cell, a remarkable improvement in the performance of the solar cell is achieved. When temperature increase by 10K, the short circuit current and open circuit voltage are enhanced by ~0,05mA/cm2 and ~0,0022 respectively. The optimal values of the solar cell parameters obtained in this study are: Jsc≈ 31.0683 (mA/cm2), Voc=1.0173 (V), PCE = 26.72 % and FF=84.54%.
This paper presents a high performance chopper-Stabilized Two-stage operational amplifier for biomedical applications. This Two-stage is designed for low noise, low power, high PSRR and high CMRR. The Miller compensation technique (Cc) is used with a nulling active resistance (Rz) implemented using Transmission gate (TG) transistors for stable operation in feedback mode. Chopper stabilization technique has been widely used in amplifiers for flicker (1/f) noise and offsets reduction purposes using the principles of modulation and demodulation. Thus, the functionality and performance of modulation and demodulation circuits determines the realization and attainment of chopper stabilization. The operational amplifier was manufactured in a SPECTRE using GPDK 90nm CMOS technology with threshold voltages of a 0.17 V and -0.14 V achieve a low power 2.6uW, Hz nV / 5 . 13at 10Hz high CMRR up to 130dB and PSRR up to 70dB at 1V power supply.
This work addresses the issue related to the electronic transport in the III−V ternary material Ga 0.5 In 0.5 Sb using Monte Carlo method. We investigated the electronic motion in the three valleys Ŵ, L, and X of the conduction band. These three valleys are isotropic, non-parabolic and centred on the first Brillouin zone. In our study, we included scatterings with ionised impurities, acoustic and polar optical phonons, as well as, intervalley and intravalley interactions. We discussed the electronic transport characteristics at the stationary and the transient regimes in function of temperature and electric field.
In a comparative framework, an ensemble Monte Carlo was used to elaborate the electron transport characteristics in two different silicon carbide (SiC) polytypes 3C-SiC and 4H-SiC. The simulation was performed using three-valley band structure model. These valleys are spherical and nonparabolic. The aim of this work is to forward the trajectory of 20,000 electrons under high-flied (from 50 kV to 600 kV) and high-temperature (from 200 K to 700 K). We note that this model has already been used in other studies of many Zincblende or Wurtzite semiconductors. The obtained results, compared with results found in many previous studies, show a notable drift velocity overshoot. This last appears in subpicoseconds transient regime and this overshoot is directly attached to the applied electric field and lattice temperature.
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