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Pressure effects in RF and DC sputtered Sb2Te3 thin films and its applications into solar cells
摘要： In this work we developed the synthesis and characterization of Sb2Te3 thin films, which were grown by RF as well as DC sputtering as a function of the deposition pressure (Pd), 5–15 mTorr. Sb2Te3 films were characterized through X-Ray Diffraction, Energy Dispersive Spectrometry (EDS), Scanning Electron Microscopy (SEM) and electrical resistivity measurements. As a part, contact layer, of the CdTe-based Solar Cell, Current-Voltage (I–V) as well as External Quantum Efficiency (EQE) measurements were carried out. Our results indicate that the radio-frequency sputtered Sb2Te3 are polycrystalline with predominant rhombohedral crystalline structure, whereas the DC-sputtered films crystallized mainly in the monoclinical structure. Both set of samples showed a resistivity of the order of 10?4 Ω-cm. Concerning the CdTe-based solar cell, the incorporation of the Sb2Te3 as a back surface film in the back contact improves the solar cell efficiency up to 8.01%, 10 mTorr pressures into the growth chamber, as compared to the CdTe-based solar cell, 4.82% efficiency, without the Sb2Te3 layer.
关键词： p+ material,CdTe solar cells,Sputtering RF and DC,Sb2Te3
更新于2025-11-14 15:15:56
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Evaluation of solar factor using spectral analysis for CdTe photovoltaic glazing
摘要： Solar and luminous light transmission control using Cadmium Telluride (CdTe) based PV glazing systems (15cm × 15 cm × 0.6 cm) were evaluated in this work. Indoor spectral characterisation showed that average solar transmission for investigated three different CdTe glazing systems were 5.77% (CdTe1), 9.54% (CdTe2) and 12.34% (CdTe3). Spectral behaviour of reflections in the range of solar and visible wavelengths was similar for these three different transparent CdTe glazing. Near infrared (NIR) reflection was higher compared to luminous reflection after 1500 nm for all three glazing systems. Solar factor (SF) for CdTe1, CdTe2 and CdTe3 glazing were 0.23, 0.28, 0.26. CdTe3 is the best candidate for glazing application as it has 113% higher luminous transmission while SF only increases by 21% compared to CdTe1.
关键词： transmission,reflection,solar factor,glazing,Cadmium Telluride (CdTe),thin film solar cell
更新于2025-10-22 19:40:53
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI, USA (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Commercial Test of Anti-Reflective Coating on First Solar Cadmium Telluride PV Modules
摘要： Anti-reflective coatings (ARC) are commonly applied to photovoltaic (PV) modules in the solar industry to increase power and energy output. In addition to characterization of initial module power and angle of incidence modifier (IAM), it is important to verify that the expected gain is observed in commercial system operation. This analysis shows the increased performance of ARC First Solar CdTe PV modules compared to non-ARC equivalent modules in a commercial test in New South Wales, Australia. PPI analysis indicates a sustained ARC performance gain over time, suggesting good ARC durability. Detailed actual-expected analysis shows both array types performing at or above expected levels after almost 2 years in the field. ARC arrays show slightly greater benefit than predicted compared to non-ARC arrays.
关键词： CdTe thin film photovoltaics,solar power generation,performance analysis,photovoltaic systems,PV anti-reflective coatings,solar energy
更新于2025-09-23 15:23:52
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Study on the preparation of CdTe nanocrystals on the surface of mesoporous silica and evaluation as modifier of carbon paste electrodes
摘要： Here CdTe nanocrystals were grown onto mesoporous silicas. The influence of the surface areas, volumes and pore diameters of the silica matrices on the spectroscopic properties of CdTe was evaluated. Emission properties of the CdTe were found to depend on the textural properties of silicas. Electrochemical characterization of different electrodes (unmodified carbon paste, and carbon paste modified with the mesoporous silica and with CdTe anchored onto mesoporous silica) evidenced that the presence of CdTe nanocrystals lead to a significant increase of the anodic peak referring to Cu2+ detection. The electrode with optimal characteristics responded to Cu2+ in the linear range from 5.0 × 10?8 to 2.3 × 10?6 mol L?1 and the calculated limit of detection was 6.4 × 10?8 mol L?1. The method developed here proved to be efficient for monitoring Cu2+ in sugar cane spirit (cacha?a), with quantitative results comparable to those obtained from Flame Atomic Absorbtion Spectroscopy.
关键词： CdTe nanocrystals,Mesoporous silicas,Electrochemical sensors
更新于2025-09-23 15:23:52
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Synthesis of color-tunable CdTe/CdS:Mn core-shell nanocrystal emitters
摘要： This study presents CdTe/CdS:Mn core–shell nanocrystals (NCs) prepared in aqueous media, using thioglycolic acid as capping agent. Firstly, CdTe NCs were synthesized, and then, Mn-doped CdS shell were deposited on the top of the CdTe core under Ar atmosphere. The NCs were structurally and optically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), X-ray photoelectron (XPS), photoluminescence (PL), and Fourier transform infrared (FTIR) spectroscopy. The results obtained from XRD, XPS, PL, and EDX showed that the Mn ions were successfully introduced into the nanocrystalline shells. Moreover, the effect of Mn concentrations on the optical properties of the synthesized core-shell NCs was investigated. The effective band gap of the sample is in an indirect relationship with the Mn : Cd molar ratio, confirmed by PL analysis, and PL emissions can be measured at various wavelengths. The PL spectra showed 990 and 170 percent enhancement in the emission intensity of CdTe/CdS:Mn core/shell NCs (Mn: Cd 2.5%) compared to CdTe NCs and CdTe/CdS core/shell NCs, respectively. Consequently, the introduction of Mn dopants into the core-shell structures not only diminishes the density of quenching centers, but also reduces the effective band gap energies.
关键词： Core/Shell,Doping,Nanocrystals,CdTe/CdS:Mn,Luminescence
更新于2025-09-23 15:23:52
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Symmetry and thermodynamics of tellurium vacancies in cadmium telluride
摘要： The equilibrium geometries and thermodynamic properties of anion vacancies in cadmium telluride, as predicted by density functional theory, are revisited using semilocal and hybrid density functionals. We find that stable configurations in different charge states can only be found after a systematic search considering several starting geometries. The stable charge states, 0 and 2+, display closed-shell electronic configurations, without deep bandgap levels. The 2+ charge state has a Td symmetry with an outward relaxation, while the neutral state is a mixture of configurations with C2v and C3v symmetries, both with the same energy and a negligible energy barrier. Therefore, the neutral charge state presents an effective Td symmetry. Configurations with different symmetries, e.g., D2d, can exist as metastable states. We show that certain configurations may seem falsely stable due to several facts: the bandgap error of generalized gradient approximation, the k-point sampling used in small supercells, or the use of a restricted set of starting geometries. We believe that the HSE06 hybrid functional allows to obtain accurate formation energies and geometries. We analyze the effect of the spin-orbit coupling and GW quasiparticle corrections to the HSE06 results, and find no qualitative differences. The spin-orbit coupling and GW corrections to the HSE06 energies partially cancel each other. Finally, we investigate the divacancy VCdVTe. The obtained formation energies suggest that isolated tellurium vacancies in neutral charge state can be found only in Te-poor growth conditions, coexisting with divacancies.
关键词： CdTe,defects,vacancy,cadmium telluride
更新于2025-09-23 15:23:52
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Vapor Phase Epitaxy of (133) and (211) CdTe on (211) Si Substrates Using Metallic Cd Source
摘要： Single-crystalline CdTe films were grown in both (133) and (211) surface orientations on (211) Si substrates by vapor-phase epitaxy using metallic Cd source as a group-II precursor. The orientation of epitaxial films depended on the ratio of group-II and -VI precursors, i.e., II/VI. The orientation of epitaxial films was changed from (133) to (211) by increasing the II/VI under the CdTe growth condition. The surface morphology for (133) CdTe was smooth, whereas the surface for (211) CdTe was composed of hillocks with (111), (110), (101), and (100) facets. The full width at half maximum (FWHM) of the epitaxial films with the same thickness showed that the crystalline quality of (133) CdTe was better than that of (211) CdTe. The dependence of the orientation between (133) and (211) CdTe films on (211) Si substrates on the II/VI was explained by the difference between the step-flow growth on the step and the spontaneous nucleation on the terrace.
关键词： vapor phase epitaxy,twin,metallic cadmium,CdTe,II/VI
更新于2025-09-23 15:22:29
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Accuracy validation of incident photon fluence on detective quantum efficiency in mammography
摘要： X-ray image evaluation is commonly performed by determining the detective quantum efficiency (DQE). DQE is calculated with a presampled modulation transfer function (MTF), incident photon fluence, and digital noise power spectrum (NPS). Accurate evaluation of MTF, incident photon fluence, and NPS is important for precise DQE determination. In this study, we focused on the accuracy of the incident photon fluence in mammography. The incident photon fluence is calculated using the squared signal-to-noise ratio (SNRin^2) value as specified in the International Electrotechnical Commission (IEC) 62220-1-2 report. However, the reported SNRin^2 values were determined using a computer program, and the reported values may differ from those calculated from an X-ray spectrum that is measured with actual mammography equipment. Therefore, we evaluated the error range of reported SNRin^2 values in mammography to assess the accuracy of the incident photon fluence. First, X-ray spectra from various mammography systems were measured with a CdTe spectrometer. Six mammographic X-ray units were used in this study. Second, the SNRin^2 values were calculated from the measured X-ray spectra. The calculated values were compared to the reported values. The results show that the percentage differences between the calculated and reported SNRin^2 values were within -4.1% of each other. The results obtained in this study indicate that the SNRin^2 values provided in the IEC report are a robust and convenient tool for calculating the incident photon fluence for DQE evaluation in mammography.
关键词： Incident photon fluence,CdTe spectrometer,Mammographic X-ray spectroscopy,Detective quantum efficiency
更新于2025-09-23 15:22:29
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Tellurium Precursor for Nanocrystal Synthesis: Tris(dimethylamino)phosphine Telluride
摘要： Preparations of CdTe quantum platelets, magic-size (CdTe)13 nanoclusters, and CdTe quantum wires are described using (Me2N)3PTe (with (Me2N)3P) as a Te precursor. The (Me2N)3PTe/(Me2N)3P precursor mixture is shown to be more reactive than mixtures of trialkylphosphine tellurides and the corresponding trialkylphosphines, R3PTe/R3P, which are commonly employed in nanocrystal syntheses. For syntheses conducted in primary amine solvents, (Me2N)3PTe and (Me2N)3P undergo a transamination reaction, affording (Me2N)x(RHN)3?xPTe and (Me2N)x(RHN)3?xP (R = n-octyl or oleyl). The transaminated (Me2N)x(RHN)3?xPTe derivatives are shown to be the likely Te precursors under those conditions. The enhanced reactivities of the tris(amino)phosphine tellurides are ascribed to increased nucleophilicity due to the amino-N lone pairs.
关键词： tris(dimethylamino)phosphine telluride,tellurium precursor,CdTe quantum wires,nanocrystal synthesis,CdTe nanoplatelets,(CdTe)13
更新于2025-09-23 15:21:21
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Digital pulse timing with semiconductor gamma-ray detectors using a wavelet transform technique
摘要： Obtaining precise timing information from semiconductor gamma-ray detectors is of great interest for a variety of applications such as high-resolution positron emission tomography. However, pulse timing with these detectors through the common constant-fraction discrimination (CFD) method is strongly affected by the time-walk error that results from the inherent variations in the shape of the detectors’ pulses. This paper reports on the use of the wavelet transform for minimizing the time-walk error in digital CFD pulse timing with semiconductor gamma-ray detectors. The details of the method are described, and the experimental results with a 1 mm thick CdTe detector are shown. It is demonstrated that, by using the Haar wavelet transform of the digitized preampli?er pulses, the original tailed time spectrum of the detector with a time resolution of 8.22 ± 0.12 ns at full-width at half-maximum (FWHM) in the energy range of 300-550 keV improves to a symmetric time spectrum with a time resolution of 3.39 ± 0.02 ns (FWHM).
关键词： wavelet transform,time-walk error,CdTe detector,digital pulse timing,semiconductor gamma-ray detectors
更新于2025-09-23 15:21:21