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Chemical Bonding States and Dopant Redistribution of Heavily Phosphorus-doped Epitaxial Silicon Films: Effects of Millisecond Laser Annealing and Doping Concentration
摘要： We investigated the effect of millisecond (ms) laser annealing and doping concentration on the chemical bonding states and dopant behaviors of P-doped epitaxial Si (Si:P) layers grown on Si (100) substrates using high-resolution X-ray photoelectron spectroscopy (HR-XPS), secondary-ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) measurements. Our XPS results showed that the intensities of P 2p peaks for Si:P films were increased with P concentration and subsequent laser annealing. From the SIMS and AES measurement results, we found that P atoms were slightly accumulated at the near-surface region of the Si:P film by the laser annealing, while macroscopic P concentration being maintained in the whole Si:P films without significant diffusion of P atoms toward the Si (100) substrate. In addition, we performed ex-situ HF cleaning on the as-grown and laser-annealed Si:P films in order to precisely measure the change in chemical states and dopant distribution at the near-surface region. The intensities of the P 2p peak in the as-grown Si:P films were increased after the HF cleaning due to the removal of native oxide layers from the Si:P films. In contrast, the decrease in P 2p peak intensities was observed in the laser-annealed Si:P films after the HF cleaning, indicating the dopant loss from the near-surface region with native oxide removal.
关键词： Millisecond laser annealing,Dopant redistribution,Chemical bonding states,Phosphorus-doped epitaxial silicon films,Doping concentration
更新于2025-09-19 17:13:59
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Carbazole-Based Hole-Transport Materials for High-Efficiency and Stable Perovskite Solar Cells
摘要： As organic–inorganic halide perovskite solar cells (PSCs) near commercialization, stability challenges during real-world conditions, such as elevated temperatures, still need to be addressed. We have previously reported triarylamine-based hole transport layers (HTLs) doped with a triarylamine-based radical cation salt (EHCz-3EtCz/EH44-ox) lead to enhanced PSC stability at elevated temperatures. While it was shown the radical cation dopant did not need to be identical to the HTL matrix, little was known about dopant exchange to realize maximum impact on device-level properties (e.g., increase the low intrinsic conductivity, mobility, hydrophobic properties, synthetic ease and thermal stability). In this paper, we study the impact of dopant exchange among stable, low cost, high glass transition temperature (Tg), and easily synthesized triarylamine-based HTL and radical triarylamine cation salts as dopants. Using EH44-ox as dopant leads to the improved device-level PCE for all HTL matrices assessed. Moreover, increasing the number of ethylhexyl chains from one to two per molecule, and positioning these chains at the periphery rather than the core resulted in improved hydrophobicity. PSCs based on our HTL formulations have similar power conversion efficiency (PCE) as that of PSCs based on commercially available HTLs, while demonstrating greatly improved device-level stability at elevated temperature.
关键词： EtCz-3EHCz,dopant exchange,hole transport layers,Perovskite solar cells,EH44-ox
更新于2025-09-19 17:13:59
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Efficient flexible Mo foil-based Cu2ZnSn(S, Se)4 solar cells from In-doping technique
摘要： Cation substitution has an important impact on the power conversion efficiency (PCE) of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Herein, a significant PCE enhancement of flexible indium-doped CZTSSe solar cells has been achieved by partially substituting Sn4+ with In3+. Systematic measurements indicate that In doping in CZTSSe film effectively improves the crystallinity and carrier concentration of the absorber layer. Meanwhile, the treatment reduces interface recombination and band tailing by passivating deep defects and increases the open-circuit voltage (Voc) of the solar cells. By physical analysis, the key parameters for the solar cell diode such as A, J0, Rs and Rsh are significantly improved after In-doping, indicating better PN junction quality. Under the optimal In-doping (x ? In/(Sn t In) ? 9%), the flexible Cu2ZnSn1-xInx(S,Se)4 solar cell has been successfully obtained with the best efficiency of 7.19% and the Voc enhancement of 62 mV due to reduced Voc deficit and band tailing.
关键词： Solution process,In dopant,Mo foil,Flexible CZTSSe solar cells
更新于2025-09-19 17:13:59
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Optoelectronic and Electronic Properties of Tetracyanoindane for Chemical Doping of Organic Semiconductors
摘要： Chemical doping of organic semiconductors is a common technique used to increase the performance numerous organic electronic and optoelectronic devices. Tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) is one of the most widely known p-dopants having the properties necessary to act as a strong electron acceptor. Despite its strong electron accepting abilities, F4-TCNQ is extremely expensive, making it less than ideal for large-area applications. Here, we introduce a small molecule called Tetracyanoindane (TCI) as a potential p-dopant. Widely known for its role in the field of non-linear optics, its high polarizability arises from the addition of four cyano-groups, which are electron withdrawing groups. The four cyano-groups are also seen in the F4-TCNQ molecule and contributes to the withdrawing strength alongside the four fluorine atoms present. We hypothesize that TCI could have similar accepting strength to F4-TCNQ and could potentially replace it as a cheaper alternative. In this study, Cyclic Voltammetry (CV), UV-Visible-Near Infrared Spectroscopy (UV/Vis/NIR), Photoluminescence (PL), Current-Voltage (IV) measurements analysis was conducted to compare the accepting strength of TCI and F4-TCNQ. Then, the two molecules were added to Poly-3-hexy-thiophene (P3HT) to observe how readily they dope the organic semiconductor.
关键词： p-dopant,F4-TCNQ,Tetracyanoindane,Chemical doping,organic semiconductors
更新于2025-09-16 10:30:52
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Effect of Cd1-xMnxSe Alloy Thickness on the Optical and Photovoltaic Properties of Quantum Dot-Sensitized Solar Cells
摘要： In this work, the Cd1?xMnxSe alloy was successfully prepared using a successive ionic layer adsorption and reaction method to investigate the layers’ effect on the properties of devices while concentration dopant was optimized at 20% (molar concentrations between Mn2+ and Cd2+ ions in the Cd1?xMnxSe material). The layers of the Cd1?xMnxSe alloy play a role in improving the optical, photovoltaic, and electrochemical properties of the solar cells. Hence, the efficiency performance of devices based on the Cd1?xMnxSe alloy reached ～3.8%. Besides, in order to explain this result, the experimental I–V curve was also used to determine the resistances at the interfaces and the resistance diffusion of the devices. This dynamic resistance can be compared with that of electrochemical impedance spectra.
关键词： metal dopant,solar cell,photovoltaic,efficiency,nanomaterials
更新于2025-09-16 10:30:52
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Visualization of different carrier concentrations in n-type-GaN semiconductors by phase-shifting electron holography with multiple electron biprisms
摘要： Phase-shifting electron holography (PS-EH) using a transmission electron microscope (TEM) was applied to visualize layers with different concentrations of carriers activated by Si (at dopant levels of 1019, 1018, 1017 and 1016 atoms cm?3) in n-type GaN semiconductors. To precisely measure the reconstructed phase pro?les in the GaN sample, three electron biprisms were used to obtain a series of high-contrast holograms without Fresnel fringes generated by a biprism ?lament, and a cryo-focused-ion-beam (cryo-FIB) was used to prepare a uniform TEM sample with less distortion in the wide ?eld of view. All layers in a 350-nm-thick TEM sample were distinguished with 1.8-nm spatial resolution and 0.02-rad phase-resolution, and variations of step width in the phase pro?le (corresponding to depletion width) at the interfaces between the layers were also measured. Thicknesses of the active and inactive layers at each dopant level were estimated from the observed phase pro?le and the simulation of theoretical band structure. Ratio of active-layer thickness to total thickness of the TEM sample signi?cantly decreased as dopant concentration decreased; thus, a thicker TEM sample is necessary to visualize lower carrier concentrations; for example, to distinguish layers with dopant concentrations of 1016 and 1015 atoms cm?3. It was estimated that sample thickness must be more than 700 nm to make it be possible to detect sub-layers by the combination of PS-EH and cryo-FIB.
关键词： phase-shifting electron holography,dopant pro?ling,carrier concentration,GaN,inactive layer,active layer
更新于2025-09-16 10:30:52
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Thermal Activation of Boron- and Phosphorus-Doped Amorphous Silicon and the Contribution to Improved Efficiency in Hydrogenated Amorphous Silicon Solar Cells
摘要： Hydrogenated amorphous silicon (a-Si:H) is an interesting candidate as an absorber material for solar cells. Despite the wealth of research to improve the e?ciency of a-Si:H solar cells by improving either the material quality of the absorber layer or by means of light trapping approaches, e?orts to improve the e?ciency by means of doped layer manipulation are relatively rare. In this work, single-junction a-Si:H solar cells with improved e?ciency due to thermal activation of doped layers via thermal annealing will be presented. Temperature-dependent dark conductivity measurements revealed that p- and n-type doped a-Si:H materials show di?erent equilibrium temperatures. External quantum e?ciency at di?erent annealing temperatures revealed that front surface collection probability was improved with the activation of a p layer, after which the collection probability of the back surface was improved with the activation of an n layer.
关键词： Dopant activation,Amorphous silicon,Solar cells
更新于2025-09-16 10:30:52
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Making benzotrithiophene derivatives dopant-free for perovskite solar cells: Step-saving installation of π-spacers by a direct C–H arylation strategy
摘要： Previously, benzotrithiophene (BTT)-based hole-transporting materials (HTMs) had to be doped with three chemical agents for high-efficiency perovskite solar cells (PSC). This work describes significant progress by which the first dopant-free BTT core-based HTM (YKP03) with EDOT spacers was readily accessed by step-saving direct C–H arylation. PSCs with dopant-free YKP03 showed promising efficiencies of up to 16.15% with potential long-term storage stability.
关键词： direct C–H arylation,benzotrithiophene,dopant-free,perovskite solar cells,hole-transporting materials
更新于2025-09-16 10:30:52
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Optimization of Boron Spin on Dopant (BSoD) Diffusion for Emitter Formation in n-type c-Si Solar Cells
摘要： Boron spin on dopant (BSoD) is an alternative boron source to BBr3 liquid dopant for p+ emitter formation in n-type solar cells. In this work, we have used different process control steps to lower the BSoD diffusion issues to have a uniform sheet resistance of p+ emitters. After eliminating the boron (B) precipitates formed during the process of diffusion by control process steps, the emitters have been optimized for sheet resistance values ≤60?/□ with variation less than ±5?/□. The corresponding junction depth is less than 800nm as measured by SIMS analysis. All the experiments are carried out with Czochralski n-type c-Si wafers which showed an improvement of effective minority carrier lifetimes by more than 2 times in controlled process steps. The measured Sun’s Voc and implied Voc are in the range 575- 600mV without any passivation. The PC1D simulation shows the efficiency of the solar cell without any passivation is 14.8%. This indicates the BSoD as a promising source for the p+ emitter formation in n- type c-Si solar cells.
关键词： boron rich layer,Sheet resistance,boron spin on dopant,PC1D simulation
更新于2025-09-16 10:30:52
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Electrostatically Doped Silicon Nanowire Arrays for Multispectral Photodetectors
摘要： Nanowires have promising applications as photodetectors with superior ability to tune absorption with morphology. Despite their high optical absorption, the quantum efficiencies of these nanowire photodetectors remain low due to difficulties in fabricating a shallow junction using traditional doping methods. As an alternative, we report non-conventional radial heterojunction photodiodes obtained by conformal coating of indium oxide layer on silicon nanowire arrays. The indium oxide layer has a high work function which induces a strong inversion in the silicon nanowire and creates a virtual p-n junction. The resulting nanowire photodetectors show efficient carrier separation and collection leading to an improvement of quantum efficiency up to 0.2. In addition, by controlling the nanowire radii, the spectral response of the In2O3/Si nanowire photodetectors are tuned over several visible light wavelengths, creating a multispectral detector. Our approach is promising for the development of highly-efficient wavelength selective photodetectors.
关键词： electrostatic doping,nanowire photodetectors,multispectral,photosensors,silicon nanowire,dopant-free,radial junction
更新于2025-09-16 10:30:52