Article
Energy & Fuels
Bernice Mae Yu Jeco-Espaldon, Ryo Tamaki, Maxime Giteau, Hao Xu, Nazmul Ahsan, Richard R. King, Yoshitaka Okada
Summary: Perimeter recombination is one of the causes for the nonuniform luminescent coupling effect in III-V multijunction solar cells. Electrical passivation of the multijunction solar cell perimeter can significantly improve current collection and homogeneity, resulting in an increase in absolute conversion efficiency.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Multidisciplinary Sciences
Ying Kai Loh, Petra Vasko, Caitilin McManus, Andreas Heilmann, William K. Myers, Simon Aldridge
Summary: The authors prepared an unsymmetrical organoboron analogue of Thiele's hydrocarbon and studied its oxidation reactions, revealing that the radical cation is stable over a redox range of > 1 V and can be isolated. This strategy not only broadens the redox stability window of the compound but also has the potential to be extended to other transient organic radicals.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Jeonghwan Park, Kangmin Lee, Kwanyong Seo
Summary: In this study, an effective chemical treatment method was proposed to remove nanoscale surface damage from c-Si microholes in photovoltaics, achieving both transparency and high power conversion efficiency.
CELL REPORTS PHYSICAL SCIENCE
(2022)
Article
Energy & Fuels
Andreas Wolf, Julian Egle, Sebastian Mack, Hannes Hoffler, David Herrmann, Sabrina Lohmuller, Joerg Horzel, Andreas Fell
Summary: This study focuses on the effective surface recombination velocity of alkaline textured, Phosphorus-diffused, and thermal SiO2/SiNx passivated surfaces with an emphasis on the impact of the thermal oxidation temperature. By applying a recent calibration procedure for carrier lifetime measurements, precise determination of the dark saturation current density was achieved. Experimental results from various diffusion/oxidation process combinations provide a dataset for revising the parameterization of the effective surface recombination velocity and investigating the impact of oxidation temperature on passivation quality, including the modeling of fixed surface charges.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Optics
Yaonan Hou, Ilias Skandalos, Mingchu Tang, Hui Jia, Huiwen Deng, Xuezhe Yu, Yasir Noori, Spyros Stathopoulos, Siming Chen, Huiyun Liu, Alwyn Seeds, Graham Reed, Frederic Gardes
Summary: We investigate the surface and interface engineering on InAs quantum dot emitters using edge-emitting light-emitting diodes encapsulated with non-stoichiometric silicon nitride (SiN) layers. Our findings show that silicon-rich SiN is an excellent choice for both electrical and optical passivation, reducing surface recombination. However, N-rich SiN deposited by the same method does not provide effective passivation under electrical injection. This research provides important insights for the monolithic integration of InAs quantum dot emitters with CMOS photonics components.
JOURNAL OF LUMINESCENCE
(2023)
Article
Chemistry, Multidisciplinary
Benjamin A. Reeves, Myles A. Steiner, Thomas E. Carver, Ze Zhang, Aaron M. Lindenberg, Bruce M. Clemens
Summary: We successfully separated single-crystalline multilayer III-V solar cells from GaAs substrates using an unfocused Nd:YAG laser pulse. The resulting device has a power conversion efficiency of 17.4% and an open-circuit voltage of 1.07 V, comparable to cells produced via conventional processes.
CELL REPORTS PHYSICAL SCIENCE
(2023)
Article
Energy & Fuels
Olivier Richard, Artur Turala, Vincent Aimez, Maxime Darnon, Abdelatif Jaouad
Summary: Improving the performances and reducing costs of III-V multijunction solar cells by implementing non-ohmic metal/semiconductor interface contacts on the front surface of III-V/Ge triple-junction solar cells were investigated. It was found that sulfur passivation by (NH4)2Sx on the GaAs contact layer could significantly reduce reverse saturation dark current density, and the best results were obtained by simple evaporation of Al on either the GaAs contact layer or the AlInP window.
Article
Chemistry, Multidisciplinary
Changwei Yuan, Mengda He, Xinrong Liao, Mingming Liu, Qinggang Zhang, Qun Wan, Zan Qu, Long Kong, Liang Li
Summary: This study presents a versatile post-synthesis strategy to address surface and interface defects in core-shell quantum dots. By promoting halogen diffusion within the crystal structure at elevated temperatures, the strategy effectively repairs oxidation and reduces interface defects. The findings contribute to the advancement of semiconductor nanomaterials by providing fundamental insights into interface defect engineering.
Article
Physics, Applied
Xiangyang Liu, Xinsheng Liu, Yiran Wang, Miao Liang, Chaoran Qin, Leshuai Sun, Chaofan Yan
Summary: Tin oxide has been widely used in perovskite solar cells as an alternative to titanium dioxide, with metal-doping and functional molecules playing important roles in optimizing film and enhancing device performance. In some experiments, metformin and urea were used to passivate interface traps, with metformin showing stronger interactions. Additionally, diblock polymers were incorporated to improve stability and performance.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Environmental
Bing Yan, Tian Liang, Xiaohui Yang, Ashok J. Gadgil
Summary: A novel carbonized melamine foam supported Mn(IV)-doped beta-FeOOH nanospindles material has been developed for efficient and recyclable arsenic removal, showing great potential for groundwater and wastewater treatment in mines and industry.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
Article
Energy & Fuels
Yasushi Shoji, Ryuji Oshima, Kikuo Makita, Akinori Ubukata, Takeyoshi Sugaya
Summary: HVPE technology is used to grow high-efficiency AlInGaP solar cells, showing improved performance by introducing an AlInGaP BSF layer. In addition, tandem solar cells grown using HVPE achieve a new record efficiency by improving the performance of the InGaP top cells.
Article
Chemistry, Physical
Pengyang Wang, Bingbing Chen, Renjie Li, Sanlong Wang, Ningyu Ren, Yucheng Li, Sayantan Mazumdar, Biao Shi, Ying Zhao, Xiaodan Zhang
Summary: By introducing cobalt chloride hexahydrate (CoCl2 center dot 6H(2)O) into SnO2 film, favorable energy level alignment and better charge extraction were achieved, leading to an enhanced V-OC and efficiency. This doping method provides an effective strategy for reducing energy loss and enhancing the efficiency of perovskite solar cells.
ACS ENERGY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Emanuele Panizon, Andrea Silva, Xin Cao, Jin Wang, Clemens Bechinger, Andrea Vanossi, Erio Tosatti, Nicola Manini
Summary: The understanding of nano-scale friction, governed by atomic arrangements, is incomplete. This study provides a unified understanding of friction by researching the potential energy of contacting surfaces and categorizing contacts into three types based on geometrical features. These types include structurally lubricated contacts, corrugated and interlocked contacts, and a newly discovered directionally structurally lubricated contact. The findings have implications for a wide range of materials in contact.
Article
Nanoscience & Nanotechnology
Hang Cheong Sio, Di Kang, Rong Liu, Josua Stuckelberger, Christian Samundsett, Daniel Macdonald
Summary: This study investigates the use of fluorine to passivate defects in silicon for solar cell applications. The results show that fluorine incorporation improves interfaces and passivates bulk defects in silicon, comparable to hydrogentation. This opens up new opportunities to improve solar cell performance by combining fluorination and hydrogenation.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Charlotte Weiss, Jonas Schon, Oliver Hohn, Bianca Fuhrmann, Frank Dimroth, Stefan Janz
Summary: This study successfully integrated a passivated, highly reflecting Ge rear side into a III-V multijunction solar cell, leading to an increase in Ge cell current. Two different types of laser processes were evaluated for contact formation, both utilizing a local back surface field to preserve passivation of the contact points and achieve good back contact performance. The passivation effect was experimentally proven and qualitatively assessed with cell simulations.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Physics, Applied
Ze Feng, Xiaoye Qin, Xiao Chen, Zhiyun Li, Rong Huang, Yang Shen, Ding Ding, Yitong Wang, Meiyi Jing, Yi Cui, An Dingsun, Hui Liu, Hong Dong, Robert M. Wallace
Summary: This study investigates the diffusion of interface oxygen and indium atoms in an InP/Al2O3 stack using O-18 isotope tracing, shedding light on the fundamental mechanism for III-V semiconductors' interface elemental diffusion and the interface passivation strategy.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Antti Lahti, Ralf Ostermark, Kalevi Kokko
Summary: In this paper, we developed our structural optimization algorithm on a numerical platform called Genetic Hybrid Algorithm (GHA) and extended it to oxides. We tested the algorithm with alpha-quartz as a case study and reported the results and findings. Unit cells of different sizes were studied, and three low energy structures near the global minimum structure were identified. We compared energy-guided and structure-based guiding methods, and found that the structure-based guiding method is more reliable.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Multidisciplinary Sciences
Pauline Colinet, Hannah Byron, Sami Vuori, Juha-Pekka Lehtio, Pekka Laukkanen, Ludo Van Goethem, Mika Lastusaari, Tangui Le Bahers
Summary: This study reports and compares the photochromic properties of three aluminosilicate natural minerals. An innovative experimental and computational approach is used to understand the origin of these properties. The stability of the colored form is found to be related to the motion of sodium atoms.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Materials Science, Multidisciplinary
Juha-Pekka Lehtio, Zahra Jahanshah Rad, Marko Punkkinen, Risto Punkkinen, Mikhail Kuzmin, Pekka Laukkanen, Kalevi Kokko
Summary: In this study, the formation mechanism and parameters affecting the negative fixed charge at the Si/high-k material interface after high-temperature annealing were investigated. The effects of annealing temperature and high-k film thickness on the charge formation were demonstrated. The structural modification of the interface produced by annealing was observed and its impact on the electronic structure of the interface was analyzed through ab initio calculations.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
Masoud Ebrahimzadeh, Sami Vuori, Mikko Miettinen, Juha-Pekka Lehtio, Sari Granroth, Marko P. J. Punkkinen, Zahra Sadat Jahanshah Rad, Risto Punkkinen, Mikhail Kuzmin, Pekka Laukkanen, Mika Lastusaari, Kalevi Kokko
Summary: Properties of oxidized InP surfaces are important for developing passivation of III-V crystals. Exposure to NH3 or O-2 gas at low temperatures can modify InP native oxides. NH3 exposure increases photoluminescence intensity for n-InP crystals with native oxide, while O-2 exposure increases it for p-type InP crystals.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(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
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
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, Multidisciplinary
Xinglu Wang, Yaoqiao Hu, Seong Yeoul Kim, Rafik Addou, Kyeongjae Cho, Robert M. Wallace
Summary: This study investigates the origins of Fermi level (E-F) pinning for Ni and Ag contacts on W-TMDs by considering interface chemistry, band alignment, impurities, and imperfections of W-TMDs, contact metal adsorption mechanism, and the resultant electronic structure. The origins of E-F pinning at a covalent contact metal/W-TMD interface are defects, impurities, and interface reaction products, while for a van der Waals contact metal/TMD system, the primary factor responsible for E-F pinning is the electronic modification of the TMDs resulting from defects and impurities.
Article
Materials Science, Multidisciplinary
Masoud Ebrahimzadeh, Sari Granroth, Sami Vuori, Marko Punkkinen, Mikko Miettinen, Risto Punkkinen, Mikhail Kuzmin, Pekka Laukkanen, Mika Lastusaari, Kalevi Kokko
Summary: Successful reduction of contact resistivity on p-InP crystals was achieved through wet-chemistry treatments and nanoscale control, improving the durability and conductivity of the devices.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Sami Vuori, Pauline Colinet, Juha-Pekka Lehtio, Arnaud Lemiere, Isabella Norrbo, Micael Granstrom, Jari Konu, Goran Agren, Pekka Laukkanen, Laeticia Petit, Anu J. Airaksinen, Ludo van Goethem, Tangui Le Bahers, Mika Lastusaari
Summary: In this study, a sustainable solution for radiochromic detection is proposed using hackmanite, a natural intelligent material. Experimental evidence shows that hackmanite exhibits radiochromic properties when exposed to different particles and radiation, and the mechanism of gamma-induced radiochromism in hackmanite is elucidated using both experimental and computational data. Hackmanite can be used for gamma dose mapping in high dose applications and has the ability to remember earlier gamma exposure, making it a promising replacement for the currently available radiochromic films. It is also non-toxic and reusable.
MATERIALS HORIZONS
(2022)
Article
Chemistry, Physical
Mikhail Kuzmin, Juha-Pekka Lehtio, Zahra Jahanshah Rad, Svetlana V. Sorokina, Marko P. J. Punkkinen, Hannu-Pekka Hedman, Risto Punkkinen, Pekka Laukkanen, Kalevi Kokko
Summary: Studied the oxidation process and electronic properties of Si-alloyed Ge interfaces. Found that the incorporation of Si strengthens the Ge-O bonds and increases the oxygen content in the oxide/Ge junctions, which helps decrease the defect-level densities.