Article
Materials Science, Multidisciplinary
Gagik Ayvazyan, Levon Hakhoyan, Karen Ayvazyan, Arthur Aghabekyan
Summary: Black silicon (b-Si) is used as an external gettering layer to remove metallic impurities and defects from silicon during thermal activation. The efficiency of gettering is evaluated based on resistivity, defect density, interstitial iron concentration, and minority carrier lifetime. Thermal oxidation process reveals that b-Si effectively traps excess iron atoms and other fast-diffusing impurities, reducing stacking faults and improving carrier lifetime. Furthermore, the application of b-Si in solar cell fabrication improves all electronic parameters, resulting in increased conversion efficiency.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Thermodynamics
Ilias Bouchkira, Saad Benjelloun, Lhachmi Khamar, Abderrazak M. Latifi
Summary: In this work, a thermodynamic-based model of an industrial phosphoric acid process is developed and validated using experimental measurements and global estimability analysis. The validated model can now be used for predicting properties needed for the simulation and optimization of the industrial process.
FLUID PHASE EQUILIBRIA
(2023)
Article
Physics, Applied
Shingo Kariya, Takashi Matsumae, Yuichi Kurashima, Hideki Takagi, Masanori Hayase, Eiji Higurashi
Summary: An Au/Ta/Ti metal multilayer was developed to improve the high vacuum packaging process for microdevice fabrication. The study showed that the coated wafer could form direct bonding and absorb residual gas, and investigated the effect of Ta layer thickness on Ti atom diffusion.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Yujin Jung, Kwan Hong Min, Regina Post, Wolfram Kwapil, Martin C. Schubert, Donghwan Kim, Yoonmook Kang, Hae-Seok Lee
Summary: Improving electrical and optical properties is vital in the manufacturing of high-efficiency solar cells. This study introduces a novel method called saw damage gettering with texturing that combines the benefits of individual gettering and texturing techniques for multicrystalline silicon wafers. The results demonstrate that this method effectively improves the performance of solar cells and could be applicable for future use.
Article
Energy & Fuels
N. Dasilva-Villanueva, S. Catalan-Gomez, D. Fuertes Marron, J. J. Torres, M. Garcia-Corpas, C. del Canizo
Summary: UMG silicon has become a promising alternative material for solar cells due to its low cost and environmental impact. However, UMG-based cell efficiencies vary over wider ranges, with higher defect density and compensated doping character. Different samples were analyzed, showing the impact of carrier trapping, especially after a phosphorous diffusion gettering (PDG) process, which improved minority carrier lifetime in mc-Si samples. The study also discussed the influence of dislocations clusters and the role of oxygen in the material.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Review
Energy & Fuels
AnYao Liu, Sieu Pheng Phang, Daniel Macdonald
Summary: This article focuses on the importance of gettering techniques in silicon-based PV devices to improve efficiency, discussing various capture approaches and their impacts on device performance.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Chemistry, Physical
Jonas Amsler, Philipp N. Plessow, Felix Studt
Summary: The relevance of organic impurities for the initiation of the MTO process varies depending on the type and partial pressures of the impurities. In the kinetic model, even small quantities of impurities such as ethanol can lead to faster initiation compared to direct C-C bond formation, which is only significant in the absence of impurities.
Article
Biology
Lea Krutzke, Reinhild Roesler, Ellen Allmendinger, Tatjana Engler, Sebastian Wiese, Stefan Kochanek
Summary: ChAdOx1 nCoV-19 vaccine contains higher than expected levels of host cell proteins (HCPs) and free viral proteins, while Ad26.COV2.S vaccine has low amounts of HCPs. The purification procedures of ChAdOx1 nCoV-19 vaccine should be modified to remove protein impurities, and standard quality assays for protein manufacturing need to be adapted for vectored vaccines.
Article
Engineering, Electrical & Electronic
Ryo Hirose, Takeshi Kadono, Ayumi Onaka-Masada, Ryosuke Okuyama, Koji Kobayashi, Akihiro Suzuki, Yoshihiro Koga, Kazunari Kurita
Summary: The novel hybrid molecular ion implantation technique for proximity gettering effectively reduced carbon dose by forming silicon extrinsic Frank-type dislocation loops after epitaxial growth. Nickel and copper gettering test results showed that the ion-implanted region can capture Ni and Cu contaminants with lower carbon dose compared to hydrocarbon-molecular-ion-implanted wafers. The end of range defects (EOR) were observed to act as gettering sites, suggesting relaxation-type and segregation-type gettering induced by this technique.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Chemistry, Analytical
Yanqing Chen, Huiliang Li, Hang Hong, Hongwen Tao, Xianglin Peng, Guangyu Xu
Summary: Empagliflozin is an effective SGLT2 inhibitor for improving glycemic control in adults with type 2 diabetes. During its manufacturing process, three unknown impurities were discovered in pilot batches, and their structures were elucidated through comprehensive analysis. Mechanistic pathways to the formation of these impurities were also discussed.
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
(2021)
Article
Chemistry, Analytical
Hongyi Yan, Yabo Wang, Yongli Yue, Li Li, Xiaowei Shi, Kai Zhang, Na Xue
Summary: This study reported on the identification and characterization of 11 process-related impurities in the preparation of Evocalcet, as well as discussed the possible formation pathways and synthetic methods of 10 of these impurities.
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
(2022)
Article
Food Science & Technology
Tao Li, Jinjie Tong, Muhua Liu, Mingyin Yao, Zhifeng Xiao, Chengjie Li
Summary: In this study, an automatic approach based on machine vision technology is proposed for corn image acquisition, impurity classification and recognition, and impurities content detection. The MSRCR algorithm is used to enhance the image, HSV color space parameter threshold is set for image segmentation, and a comprehensive evaluation index is adopted for quantitatively evaluating the test results. The online detection results show the effectiveness of the proposed algorithm in identifying impurities in corn images and monitoring impurities content in the corn deep-bed drying process.
Article
Chemistry, Multidisciplinary
Ganyu Zhu, Yunrui Yang, Lei He, Huiquan Li, Ziheng Meng, Guangming Zheng, Fang Li, Xiaodan Su, Benjun Xi, Zhongjun Li
Summary: Phosphogypsum, a byproduct of wet-process phosphoric acid reaction, has led to environmental pollution issues. By establishing a liquid-solid-liquid three-phase acid hydrolysis synergistic extraction reaction system in the actual production process with the addition of a certain amount of extractant, the property and purity of phosphogypsum in the wet-process phosphoric acid process can be improved. The extraction effect and residue of impurities in the reaction system were systematically analyzed through the study of the phase, morphology, and impurity occurrences of phosphogypsum. The results showed that the conversion of P2O5 was the highest in phosphate rock under certain reaction conditions, and the residual P2O5 content in phosphogypsum was as low as 0.36%. The morphology of the phosphogypsum crystal was uniform and coarse long strip, and the residual impurities mainly consisted of silicate, aluminum fluoride with crystal water, aluminate, phosphate, and fluoride. This novel method greatly improves the property of phosphogypsum and promotes its utilization and the recycling development of the wet-process phosphoric acid industry.
Article
Materials Science, Multidisciplinary
Sergio Catalan-Gomez, Nerea Dasilva-Villanueva, David Fuertes Marron, Carlos del Canizo
Summary: Experimental evidence shows that phosphorous diffusion gettering (PDG) has a beneficial impact on reducing trapping centers in silicon material, significantly improving carrier lifetime, and paving the way for the development of gettering strategies.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Green & Sustainable Science & Technology
Krzysztof Barbusinski, Slawomir Fajkis, Bartosz Szelag
Summary: The study optimized the splitting process of rapeseed soapstock using Response Surface Methodology, finding that phosphorus content in oil has a significant impact on all study values, reducing it can lower wastewater concentrations and increase the acid value of fatty acids.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Optics
Behrad Radfar, Kexun Chen, Olli E. Setala, Ville Vahanissi, Hele Savin, Xiaolong Liu
Summary: In this study, we investigate the surface morphology, optical absorption (400-1100 nm), and carrier lifetime of black silicon fabricated by femtosecond (fs) laser in air. We explore a wide range of cumulative fluence delivered to the sample, represented by a single parameter xi. We also examine the laser-oxidized surface layer and its impact on the mentioned properties through photoluminescence spectra measurements.
Article
Materials Science, Multidisciplinary
Hanchen Liu, Toni P. Pasanen, Tsun Hang Fung, Joonas Isometsa, Oskari Leiviska, Ville Vahanissi, Hele Savin
Summary: Silicon nitride (SiNx)-based passivation schemes show promising potential for Ge surfaces, with a higher negative charge density compared to Si samples. The post-deposition anneal process significantly reduces the surface recombination velocity in both Si and Ge samples. The addition of an atomic-layer-deposited aluminum oxide (Al2O3) layer on SiNx-coated samples effectively reduces the midgap interface defect density (D-it), while neutralizing the charge density on Ge samples.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Anastasia Matuhina, G. Krishnamurthy Grandhi, Fang Pan, Maning Liu, Harri Ali-Loytty, Hussein M. Ayedh, Antti Tukiainen, Jan-Henrik Smatt, Vile Vahanissi, Hele Savin, Jingrui Li, Patrick Rinke, Paola Vivo
Summary: In this study, CsMnCl3 nanocrystals (NCs) were synthesized in two polymorphic structures, cubic (c-CsMnCl3) and rhombohedral (r-CsMnCl3), and it was found that c-CsMnCl3 NCs were nonemissive while r-CsMnCl3 NCs exhibited red emission. The results highlight the importance of NC structures in determining their luminescence properties.
ACS APPLIED NANO MATERIALS
(2023)
Article
Physics, Applied
Hanchen Liu, Toni P. Pasanen, Oskari Leiviska, Joonas Isometsa, Tsun Hang Fung, Marko Yli-Koski, Mikko Miettinen, Pekka Laukkanen, Ville Vahanissi, Hele Savin
Summary: The excellent field-effect passivation provided by aluminum oxide (Al2O3) on germanium surfaces relies on a high negative fixed charge. However, this study investigates the surface passivation performance and charge polarity of plasma-enhanced atomic layer deposited (PEALD) silicon oxide (SiO2) on Ge. The results show that even a 3 nm thick PEALD SiO2 provides a positive charge density and a relatively good surface passivation. Furthermore, adding an ALD Al2O3 layer further improves the surface passivation.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Kexun Chen, Olli E. Setala, Xiaolong Liu, Behrad Radfar, Toni P. Pasanen, Michael D. Serue, Juha Heinonen, Hele Savin, Ville Vahanissi
Summary: Metal-assisted chemical etched (MACE) nanostructures are widely used in the solar cell industry due to their excellent optical properties and cost-efficient fabrication process. However, the photodetection community has not shown much interest in MACE due to its drawbacks. This study demonstrates the fabrication of high-performance MACE p-n photodiodes with above 90% external quantum efficiency (EQE) and low dark current using industrially applicable methods, showcasing the potential of MACE nanostructures in low-cost photodiode fabrication.
IEEE SENSORS JOURNAL
(2023)
Article
Chemistry, Physical
Shengyang Li, Hussein M. Ayedh, Marko Yli-Koski, Ville Vahanissi, Hele Savin, Jani Oksanen
Summary: In this study, n-and p-type Si photoconductors covered with silver nanoparticles were designed to demonstrate their sensitivity to the metal-assisted chemical etching (MACE) process and their ability to provide in situ information about the reaction dynamics. Experimental results showed a stronger response of both n-and p-type photoconductors to MACE compared to light intensity of 2 mW/cm2. A thermodynamic analysis of the energy levels explained the observations, highlighting the contribution of electron and hole injection from the Si/etching solution interface to the response and excitation of the photoconductors. These findings demonstrate a new chemical operating mode for photoconductors, enabling in situ monitoring of reaction dynamics and chemical sensing.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Nanoscience & Nanotechnology
Tsun Hang Fung, Joonas Isometsa, Juha-Pekka Lehtio, Toni P. Pasanen, Hanchen Liu, Oskari Leiviska, Pekka Laukkanen, Hele Savin, Ville Vahanissi
Summary: Nanostructured germanium surfaces have achieved >99% absorption in a wide wavelength range, promising high performance for optoelectronic devices. By characterizing the surface and interface properties, we identified the limiting factors for surface recombination velocity of the nanostructures and developed a surface passivation scheme using atomic-layer-deposited aluminum oxide and sequential chemical treatment. With this scheme, we achieved a low surface recombination velocity and 1% reflectance from ultraviolet to near-infrared. We discussed the impact of these results on Ge-based optoelectronic applications.
Article
Chemistry, Multidisciplinary
M. Garin, T. P. Pasanen, G. Lopez, V. Vahanissi, K. Chen, I. Martin, H. Savin
Summary: Reducing substrate thickness to cut costs is a common practice in the crystalline silicon photovoltaic industry. However, maintaining high absorption in thin wafers is a challenge. By using black-Si nanotexture on thin uncommitted wafers, ideal light trapping is achieved with wafer thicknesses as low as 40, 20, and 10 μm when paired with a back reflector. Implementing this technology in solar cells led to a 43% improvement in output power compared to reference cells.
Article
Materials Science, Coatings & Films
Nupur Bihari, Ismo T. S. Rauha, Giovanni Marin, Craig Ekstrum, Chathura de Alwis, Pierce J. Mayville, Hele Savin, Maarit Karppinen, Joshua M. Pearce
Summary: The potential of 3-D printing polymers in low-weight space flight hardware and vacuum equipment has attracted increasing interest. However, the formation mechanisms of atomic layer deposition (ALD) coatings on 3-D printed polymers are not well understood, limiting their use in vacuum environments. This study investigates the film formation mechanisms of ALD alumina on porous 3-D printed polymers, revealing that substrate porosity and polymer functionality play a dominant role in film formation behavior.
SURFACE & COATINGS TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Olli E. Seta''la'', Kexun Chen, Toni P. Pasanen, Xiaolong Liu, Behrad Radfar, Ville Va''ha''nissi, Hele Savin
Summary: By combining a nanostructured surface with an optimized implanted junction, we have addressed the issues of reflectance losses and junction recombination in detecting UV light using Si photodiodes. The performance of our design has been compared to state-of-the-art commercial counterparts, and we have achieved a significant improvement in responsivity over a wide wavelength range. The detector design presented maintains simplicity in fabrication while meeting the important figures of merit relevant to photodiodes.
Article
Crystallography
Joonas Isometsa, Zahra Jahanshah Rad, Tsun H. Fung, Hanchen Liu, Juha-Pekka Lehtio, Toni P. Pasanen, Oskari Leiviska, Mikko Miettinen, Pekka Laukkanen, Kalevi Kokko, Hele Savin, Ville Vahanissi
Summary: Germanium is a promising material for applications like field effect transistors and radiation detectors/solar cells. However, efficient passivation of germanium surfaces is challenging. The combination of HF and DIW surface cleaning with ALD Al2O3 results in a compromised quality Ge suboxide interlayer (GeOx, x < 2). By using a low-temperature heating and a controlled oxidation in a ultrahigh vacuum (LT-UHV) treatment, the composition and crystallinity of the oxide layer can be improved, leading to a reduction in interface defect density (D-it) and achieving low SRV values.
Article
Chemistry, Physical
Ramsha Khan, Hannu P. Pasanen, Harri Ali-Loytty, Hussein M. Ayedh, Jesse Saari, Ville Vahanissi, Mika Valden, Hele Savin, Nikolai V. Tkachenko
Summary: TiO2 coatings are commonly used for surface passivation and corrosion protection of silicon-based devices. The charge transfer across the TiO2/Si interface is crucial for the performance of optoelectronic devices, and its investigation was done using transient reflectance spectroscopy. The results showed that the charge transfer velocity is influenced by interfacial SiO2, heat-treatments, and carrier diffusion in TiO2. Higher heat-treatment temperature led to reduced carrier lifetime in TiO2 due to back recombination via interfacial SiO2.
SURFACES AND INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Iris Mack, Kawa Rosta, Ulviyya Quliyeva, Jennifer Ott, Toni P. Pasanen, Ville Vahanissi, Zahra Sadat Jahanshah Rad, Juha-Pekka Lehtio, Pekka Laukkanen, Caterina Soldano, Hele Savin
Summary: The quality of the oxide-semiconductor interface has a direct impact on device electrical properties and performance. Traditional characterization methods may also affect the interface. This study investigates the impact of different deposition methods on the Al2O3/Si interface, revealing that magnetron sputtering induces significant damage and a high density of positive charges, while thermal evaporation has a modest impact. Annealing repairs the damage but also affects the film's charge.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Olli E. E. Setala, Martin J. J. Prest, Konstantin D. D. Stefanov, Douglas Jordan, Matthew R. R. Soman, Ville Vahanissi, Hele Savin
Summary: By replacing traditional methods with surface nanoengineering, the performance of commercial backside illuminated CMOS image sensors can be significantly improved in terms of spectral range, photosensitivity, and dark current reduction.
Article
Chemistry, Physical
Vladyslav Matkivskyi, Oskari Leiviska, Sigurd Wenner, Hanchen Liu, Ville Vahanissi, Hele Savin, Marisa Di Sabatino, Gabriella Tranell
Summary: This study investigated the application of two widely used atomic layer deposition precursors, TDMA-Ti and TiCl4, in TiOx-based thin films as a passivating contact material for solar cells. It was found that both precursors are suitable for similar deposition temperatures (150 °C). Post-deposition annealing significantly improved the passivation properties of the TiOx film, increasing the minority carrier lifetime (tau(eff)) by over 200 μs.AlOy/TiOx stack reduced the sheet resistance by 40% compared to pure TiOx. The passivation quality of the (AlOy/TiOx) stack was found to depend on the precursor and the ratio of AlOy to TiOx deposition cycles.