Explore the vast range of titles available.

Metal-assisted chemical etching (MACE) with platinum nanoparticles (Pt-NPs) was used to produce cone-shaped macropore structures (CSMS) on the surface of p-type silicon substrates. A straightforward control of the macropore dimensions is readily obtained as the etching time is tuned during the MACE process. The surface reflectance is advantageously reduced in a wide wavelength range and a minimum of 6.6% was achieved for an etching time of 9 min. The impact of the etching current on the morphological and optical properties of the textured Si wafers was also studied, revealing a substantial decrease of the surface reflectance up to an etching current of 40 mA. Moreover, an increase of the effective minority carrier lifetime from 5.9 to 8.9 µs was obtained as the etching current increases from 5 to 50 mA, indicating a reduction of surface recombination with the enlargement of the macropores. Interestingly, the field-effect passivation of the CSMS was found to significantly increase the effective carrier lifetime by reducing the surface recombination.

In this work, the effect of heat treatment on the minority carrier lifetime (τ) in boron-doped crystalline silicon wafers coated with a silicon nitride (SiNx:H) layer has been investigated. The results showed an initial increase in τ during the early phase of light exposure of the samples, which was attributed to the presence of iron–boron complexes in the c-Si wafers. However, this enhancement was followed by a decrease associated with the formation of boron-oxygen complexes, known as light-induced degradation. Moreover, kinetic models were used to analyze defect interactions in the wafers, showing a correlation between τ behavior and hydrogen-boron complex concentrations, and related by analytical techniques. In addition, the samples were subjected to a dark annealing step, resulting in further degradation due to the firing temperature process and the presence of hydrogen atoms in the silicon nitride layer. Finally, this study provides valuable insights into defect formation mechanisms in c-Si wafers that could improve the stability and efficiency optimization of silicon-based solar cells under operating conditions.

Time-resolved photoluminescence (TRPL) is applied to determine an effective lifetime of minority charge carriers in semiconductors. Such effective lifetimes include recombination channels in the bulk as well as at the surfaces and interfaces of the device. In the case of Cu(In,Ga)Se 2 absorbers used for solar cell applications, trapping of minority carriers has also been reported to impact the effective minority carrier lifetime. Trapping can be indicated by an increased temperature dependence of the experimentally determined photoluminescence decay time when compared to the temperature dependence of Shockley-Read-Hall (SRH) recombination alone and can lead to an overestimation of the minority carrier lifetime. Here, it is shown by technology computer-aided design (TCAD) simulations and by experiment that the intentional double-graded bandgap profile of high efficiency Cu(In,Ga)Se 2 absorbers causes a temperature dependence of the PL decay time similar to trapping in case of a recombinative front surface. It is demonstrated that a passivated front surface results in a temperature dependence of the decay time that can be explained without minority carrier trapping and thus enables the assessment of the absorber quality by means of the minority carrier lifetime. Comparison with the absolute PL yield and the quasi-Fermi-level splitting (QFLS) corroborate the conclusion that the measured decay time corresponds to the bulk minority carrier lifetime of 250 ns for the double-graded CIGS absorber under investigation.

Silicon carbide (SiC) PiN diode has shown substantial promise as the freewheel diode for switch protection in a pulsed system. In this paper, we investigate the carrier lifetime (τ) modulation on pulsed current capability of SiC PiN diodes. The carrier lifetime in 4H–SiC is modulated by the generation of the Z1/2 center through neutron irradiation. Surprisingly, we found that the pulsed current of SiC PiN diodes shows a limited improvement when the carrier lifetime (τ) increases from 0.22 to 1.3 μs, while is significantly promoted as the carrier lifetime increases from 0.03 to 0.22 μs. This changing trend is obviously different from the on-state resistance, which decreases with the increased carrier lifetime. The simulation result indicates that the heat generation (i.e., maximum temperature rise) inside the PiN diodes, especially in the drift layer, is remarkably aggravated in the pulse tests for τ < 0.1 μs, but which is significantly suppressed as carrier lifetime rises to 0.2 μs and above. Therefore, the dependence of pulsed current on carrier lifetime is ascribed to the heat generation resulting from the carrier lifetime controlled conductivity modulation effect, which hence affects the temperature rise and brings about the failure of SiC PiN diodes under high pulsed current.

Understanding the recombination lifetime of charge carriers (τc $\\left(\\tau\\right)_{\\text{c}}$ ) is essential for the diverse applications of photovoltaic materials, such as perovskites. The study on the inorganic perovskite, CsPbBr3, reveals recombination dynamics exceeding 1 ms below 200 K and τc $\\left(\\tau\\right)_{\\text{c}}$approaching 100 μs at room temperature. Utilizing time‐resolved microwave‐detected photoconductivity decay in conjunction with injection dependence, it is found that τc $\\left(\\tau\\right)_{\\text{c}}$is dominated by impurity charge trapping. The observed injection dependence is well corroborated by modeling of the trap mechanism. The ultralong decay time is also consistent with photoconductivity measurements with a continuous‐wave excitation at powers corresponding to around 1 Sun irradiation. While charge‐carrier trapping may, in theory, impose limitations on the photovoltaic efficiency of single‐cell devices, it can also contribute to increased efficiency in tandem cells and find applications in photodetection, photocatalysis, and quantum information storage. Temperature‐ and power‐dependent time‐resolved microwave photoconductivity decay (TRMCD) measurements are presented on CsPbBr3 crystals for 20–300 K. Charge‐carrier lifetime is 1 ms below 200 K and 100 μs at 300 K. The injection dependent TRMCD measurements indicate the observed ultralong effect to be caused by charge‐carrier trapping in shallow traps.

A set of Ag x Cu 1 –  x GaSe 2 (0 ≤ x ≤ 1) solid solution powders has been prepared by solid-state synthesis. Using a combination of X-ray diffraction analysis and Raman spectroscopy, it has been found that the samples have a single-phase tetragonal structure (space group I -42d). It has been shown that their crystal lattice parameters do not follow Vegard’s law up to x ≈ 0.4. It has been revealed that the band gap of the samples also changes nonlinearly: initially it decreases and then increases. Studies of the low-temperature luminescence and microwave photoconductivity decay spectra have shown that a set of samples with x of 0 to ~0.4 and further in the region with x > 0.4 is characterized by an increase in the photogenerated current carrier lifetime in Ag x Cu 1 –  x GaSe 2 powders. The observed effect is apparently attributed to the replacement of deep charge carrier traps, such as selenium vacancies, by shallower cation vacancies.

In this study, we report the fabrication of high quality AZO/NRs-ZnO/n-ZnO/p-GaAs heterojunction via a novel optimized design. First of all, the electrical proprieties of gallium arsenide (GaAs) substrates were enhanced via an optimized gettering treatment that was based on a variable temperature process (VTP) resulting in an obvious increase of the effective minority carrier lifetime (τeff) from 8.3 ns to 27.6 ns, measured using time-resolved photoluminescence (TRPL). Afterward, the deposition of a zinc oxide (ZnO) emitter was optimized and examined in view of its use both as a light trapping layer (antireflection) and as the n-type partner for the p-type (GaAs) substrate. Nanorod-shaped ZnO was grown successfully on top of the emitter, as an antireflective coating (ARC), to further boost the absorption of light for a large broadband energy harvesting. The interface state of the prepared heterojunction is a key parameter to improve the prepared heterojunction performance, thus, we used laser ablation to create parallel line microgroove patterns in the GaAs front surface. We studied the effect of each step on the performance of the n-ZnO/GaAs heterojunction. The results demonstrate a significant improvement in Voc, Jsc, fill factor (FF), and an obvious enhancement in the I–V characteristics, exhibiting good diode properties, giving rise to the photovoltaic conversion efficiency (η) from 8.31% to 19.7%, more than two times higher than the reference.

Efficiency potential of crystalline Si solar cells is analyzed by considering external radiative efficiency (ERE), voltage, and fill factor losses. Crystalline Si solar cells have an efficiency potential of more than 28.5% by realizing ERE of 20% from about 5% and normalized resistance of less than 0.05 from around 0.1. Nonradiative recombination losses in single-crystalline and multicrystalline Si solar cells are also discussed. Especially, nonrecombination and resistance losses in multicrystalline Si solar cells are shown to be higher than those of single-crystalline cells. Importance of further improvement of minority-carrier lifetime in crystalline Si solar cells is suggested for further improvement of crystalline Si solar cells. High efficiency of more than 28.5% will be realized by realizing high minority-carrier lifetime of more than 30 ms. Key issues for those ends are reduction in carbon concentration of less than 1 × 1014 cm−3, oxygen precipitated and dislocations even in single-crystalline Si solar cells, and reduction in dislocation density of less than 3 × 103 cm−2 in multicrystalline Si solar cells.

This paper investigates the impact of low minority carrier lifetime areas (red-zones) in multi-crystalline silicon ingots on cell efficiency. Wafers, sliced parallel to the sidewall, were analyzed using µ-PCD and PL to determine minority lifetimes and identify crystal defects. These wafers were then processed into solar cells, and their performance was assessed through cell conversion efficiency and electroluminescence (EL) measurements. The findings reveal a decrease in minority lifetime moving from the wall inward, followed by an increase beyond approximately 14 mm. This pattern is mirrored in cell efficiency. Notably, in regions where the minority lifetime is less than 1µs, cell efficiency drastically drops, and shunting areas are visible in EL images. Conversely, in areas with lifetimes exceeding 1µs, cell efficiency returns to normal levels. These results provide guidelines for optimally cropping the sides of the ingot.

Depth profiling of the ambipolar carrier lifetime was performed in n-type, 140mm thick silicon carbide (SiC) epilayer using excitation by two-photon absorption (TPA) with a pulsed 586nm laser, and confocal measurement of time resolved photoluminescence (TRPL) decay from the excited region. A depth resolution of ≈10mm was obtained. The PL decay curves were analyzed using a recently developed formalism that takes into account the TPA excitation, carrier diffusion and surface/interface recombination. The carrier lifetime decreases near the top surface of the epitaxial layer as well as near its interface with the substrate.