Article
Energy & Fuels
Xinyu Wang, Kun Gao, Dacheng Xu, Kun Li, Chunfang Xing, Xinliang Lou, Zhaojun Su, Xinbo Yang
Summary: Surface passivation is improved by using a boron oxide/aluminum oxide stack (BOx/Al2O3) on c-Si surfaces. The BOx/Al2O3 stacks show superior passivation quality compared to Al2O3 single layers after annealing. The optimized BOx/Al2O3 passivation stack achieves very low dark current densities on n-type and p-type Cz wafers, as well as boron-doped p+ emitters.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Xiao-Ying Zhang, Jing Han, Yao-Tian Wang, Yu-Jiao Ruan, Wan-Yu Wu, Dong-Sing Wuu, Juan Zuo, Feng-Min Lai, Shui-Yang Lien, Wen-Zhang Zhu
Summary: Hafnium oxide (HfO2) thin film is studied as a passivation layer for crystalline silicon (c-Si). The electrical characterization and measurements of HfO2 films on P-type and N-type c-Si were conducted. Post annealing in different gas ambients was performed. The results reveal the potential of HfO2 for field effect and chemical passivation. The impacts of post-annealing gas ambient on passivation qualities on Si by HfO2 thin films are systematically studied.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Baochen Liao, Neeraj Dwivedi, Qiang Wang, Reuben J. Yeo, Armin G. Aberle, Charanjit S. Bhatia, Aaron Danner
Summary: This study comprehensively investigates the properties of ALD TiOx films, showing that temperature is a key parameter in controlling the film properties for c-Si surface passivation. The findings provide valuable insight for future development of high-efficiency c-Si solar cells.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
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.
Article
Nanoscience & Nanotechnology
Abigail R. Meyer, Rohan P. Chaukulkar, Noemi Leick, William Nemeth, David L. Young, Paul Stradins, Sumit Agarwal
Summary: In this study, the atomistic-level mechanism for the chemical passivation of the monocrystalline Si surface with thermally annealed Al2O3 was investigated using in situ infrared spectroscopy and photoconductance decay measurements. The results showed that surface Si-H bonds are preserved after the ALD of Al2O3 on H-terminated Si, and restructuring occurs at the c-Si/Al2O3 interface during annealing to form interfacial SiOx. Isotope labeling was used to differentiate interfacial SiD bonds on the c-Si surface from H incorporated in Al2O3, and no net migration of atomic H or D from Al2O3 to the c-Si/Al2O3 interface was observed within the sensitivity of the infrared setup. Passivation studies were also conducted on c-Si/SiO2/Al2O3 stacks, revealing that an O-2-containing atmosphere led to the best surface chemical passivation.
ACS APPLIED NANO MATERIALS
(2021)
Article
Physics, Applied
Wilhelmus J. H. (Willem-Jan) Berghuis, Jimmy Melskens, Bart Macco, Roel J. Theeuwes, Lachlan E. Black, Marcel A. Verheijen, Wilhelmus M. M. (Erwin) Kessels
Summary: Surface passivation of germanium is crucial for Ge based optoelectronic devices, and a stack of a-Si:H and Al2O3 layers was investigated for this purpose; Different deposition processes were used for a-Si:H and Al2O3 films, with the plasma-enhanced ALD process for Al2O3 showing superior performance; A high negative fixed charge density was achieved, resulting in low surface recombination velocity, making this passivation stack promising for applications like solar cells and nanolasers using p-type Ge.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Ryo Matsumura, Naoki Fukata
Summary: This study systematically investigates and characterizes the phenomenon of blistering in atomic layer-deposited aluminum oxide layers, proposing a mechanism for blister formation using a hydrogen outgassing model. It successfully detects hydrogen gas generation from the Si-Al2O3 interface using blister-penetrating Raman spectroscopy. The proposed method of suppressing blister formation through surface treatment or passivation to eliminate Si-H bonds will provide important insights applicable to various applications such as electronic devices and nanostructured solar cells.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Wilhelmus J. H. Berghuis, Jimmy Melskens, Bart Macco, Roel J. Theeuwes, Marcel A. Verheijen, Wilhelmus M. M. Kessels
Summary: The study investigated the passivation effect of Al2O3 on Ge surfaces and found that Al2O3 prepared by ALD can achieve low surface recombination velocity. The influence of different process parameters on the passivation effect was discussed.
JOURNAL OF MATERIALS RESEARCH
(2021)
Article
Energy & Fuels
Bart Macco, Bas W. H. van de Loo, Marc Dielen, Dennis G. J. A. Loeffen, Bart B. van Pelt, Nga Phung, Jimmy Melskens, Marcel A. Verheijen, Wilhelmus M. M. Kessels
Summary: Research has shown that stacks consisting of ultrathin SiO2 coated with ALD ZnO and Al2O3 provide state-of-the-art passivation for n-type crystalline silicon surfaces and additional functionalities for silicon solar cells. The Al2O3 capping layer is crucial in the passivation mechanism, while annealing can significantly improve the transparency and lateral conductivity of ZnO.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Chemistry, Multidisciplinary
Pao-Hsun Huang, Zhi-Xuan Zhang, Chia-Hsun Hsu, Wan-Yu Wu, Sin-Liang Ou, Chien-Jung Huang, Dong-Sing Wuu, Shui-Yang Lien, Wen-Zhang Zhu
Summary: This study successfully prepared functional SnOx films with specific chemical compositions and found coexisting SnO2 and Sn3O4 phases in PEALD SnOx films. With increasing substrate temperature, the film transitioned from an amorphous to a crystalline SnO2 phase, exhibiting higher mobility.
Article
Energy & Fuels
Gerard Masmitja, Eloi Ros, Rosa Almache-Hernandez, Benjamin Pusay, Isidro Martin, Cristobal Voz, Edgardo Saucedo, Joaquim Puigdollers, Pablo Ortega
Summary: This study successfully demonstrates the fabrication of high efficiency IBC c-Si(n) solar cells using transition metal oxide films as carrier-selective contacts deposited by ALD technique, achieving excellent photovoltaic efficiencies and pseudo efficiencies.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Biochemistry & Molecular Biology
Elina Kylmaoja, Faleh Abushahba, Jani Holopainen, Mikko Ritala, Juha Tuukkanen
Summary: Coating bone implants with hydroxyapatite (HA) has benefits for osseointegration, but there may be differences in monocyte differentiation and material resorption compared to natural bone. In this study, ALD-HA coating on a titanium substrate was compared with bovine bone, and it was found that ALD-HA led to the presence of non-resorbing cells instead of resorbing osteoclasts. The topographical properties of ALD-HA, such as surface roughness, may play a role in this cellular reaction.
Article
Nanoscience & Nanotechnology
Dae Seon Kwon, Woojin Jeon, Dong Gun Kim, Tae Kyun Kim, Haengha Seo, Junil Lim, Cheol Seong Hwang
Summary: This study compared the performance of ruthenium (Ru) thin films deposited via ALD as bottom electrodes for DRAM capacitors. Using DFM-ALD improved the surface morphology of the Ru films and increased the proportion of RuO2 formation during subsequent TiO2 ALD, leading to higher crystallinity in TiO2 films. Depositing bottom electrodes using DFM-ALD reduced the EOT values while still meeting DRAM leakage current density specifications.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Nanoscience & Nanotechnology
Sang Youn Chae, Yoolim Kim, Eun Duck Park, Sang Hyuk Im, Oh-Shim Joo
Summary: The application of the (Ta,Mo)(x)(O,S)(y) atomic gradient passivation layer leads to promising photocurrent and onset potential for CuInS2-based photocathodes, without the need for Pt cocatalysts. The improved electron transient time and boosted electrocatalytic activity contribute to the excellent photoelectrochemical performance of the photoelectrode.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
Josiah Yarbrough, Stacey F. Bent
Summary: This study explores the use of 1-nitropropane as a small molecule inhibitor for selective atomic layer deposition. The results show that 1-nitropropane selectively chemisorbs on Cu and CuOx substrates, forming a high-quality inhibition layer. A new multistep process is developed for low-temperature Al2O3 ALD, allowing sequential reapplied and etched of the SMIs. The resulting area-selective ALD process enables high selectivity and could expand selective growth schemes to temperature-sensitive substrates.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Energy & Fuels
Utkarshaa Varshney, Moonyong Kim, Muhammad Umair Khan, Phillip Hamer, Catherine Chan, Malcolm Abbott, Bram Hoex
Summary: The study found that thinner silicon wafers are not naturally immune to Light and elevated-temperature-induced degradation (LeTID) and can still be affected at high temperatures. Thinner wafers do not necessarily exhibit faster recovery rates, and the higher hydrogen out-diffusion in thinner wafers during firing may lead to reduced degradation. The method used for thinning the wafers results in surface morphology variations, which could partly explain the correlation between wafer thickness and LeTID extent.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Giuseppe Scardera, Shaozhou Wang, Yu Zhang, Muhammad Umair Khan, Shuai Zou, Daqi Zhang, Rasmus Schmidt Davidsen, Ole Hansen, Ly Mai, David N. R. Payne, Bram Hoex, Malcolm D. Abbott
Summary: This article investigates the impact of specific surface area (SSA) on sheet resistance in the integration of nanotextured black silicon (B-Si) into solar cells. The study suggests that SSA is a better indicator for reducing sheet resistance. Doping level of B-Si increases with higher SSA, as indicated by 2-D dopant contrast imaging, and 3-D diffusion simulations show that radial doping and metallurgical junction depth also increase with higher SSA.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Review
Energy & Fuels
Leiping Duan, Bram Hoex, Ashraf Uddin
Summary: Opaque and semitransparent organic solar cells have made significant progress in recent years, with efficiencies reaching over 18% and 13% respectively. These solar cells do not contain harmful elements such as lead, making them suitable for a wide range of applications. There is great potential for emerging applications such as building-integrated photovoltaics, and ongoing research aims to further enhance the performance and application potential of ST-OSCs.
Article
Nanoscience & Nanotechnology
Jingnan Tong, Tien T. Le, Wensheng Liang, Md Anower Hossain, Keith R. McIntosh, Parvathala Narangari, Stephane Armand, Teng C. Kho, Kean T. Khoo, Yahya Zakaria, Amir A. Abdallah, Sachin Surve, Marco Ernst, Bram Hoex, Kean Chern Fong
Summary: The study examines the potential benefits of controlling the properties of the SiOx interlayer by introducing a pregrown high-quality SiOx, which inhibits the formation of low-quality SiOx during metal oxide deposition. It demonstrates that a high-quality pregrown SiOx reduces interfacial reaction, resulting in more stoichiometric MoOx with improved surface passivation and thermal stability.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Giuseppe Scardera, David N. R. Payne, Muhammad Umair Khan, Yu Zhang, Anastasia Soeriyadi, Shuai Zou, Daqi Zhang, Rasmus Schmidt Davidsen, Ole Hansen, Bram Hoex, Malcolm David Abbott
Summary: This study demonstrates a correlation between silicon's ultraviolet reflectance peak R(E2) and enhanced area factor (EAF) for high-resolution spatial mapping of silicon nanotextures, as well as the impact of nanotexture spatial variation on post-diffusion sheet resistance. Finite-difference time-domain simulations confirm the correlation, suggesting the potential usefulness of R(E2) mapping for other silicon nanotexture properties and applications where EAF is important.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Md. Anower Hossain, Tian Zhang, Yahya Zakaria, Daniel Lambert, Patrick Burr, Sergey Rashkeev, Amir Abdallah, Bram Hoex
Summary: Transition metal oxides like NiO have shown potential as hole-selective passivating contact for crystalline silicon solar cells, but doping with multivalent metal cations such as Al, Mg, and Zn can improve their hole-conducting properties and ohmic contact with c-Si. Experimental synthesis of Al-doped NiO films onto c-Si has demonstrated improved contact resistivity compared to undoped NiO, opening up possibilities for future applications in solar cells and other functional materials.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Shaozhou Wang, Xinyuan Wu, Fa-Jun Ma, David Payne, Malcolm Abbott, Bram Hoex
Summary: The study focuses on the surface passivation of black silicon (b-Si) and control of charge carriers in nanofeatures of b-Si surfaces. Compression of space charge region is found in b-Si nanofeatures, leading to reduction in surface minority charge carrier density and surface recombination losses. The behavior of surface passivation films is complex, with little space charge compression for b-Si with high fixed charge density, indicating that enhanced reduction of surface recombination by field-effect passivation may not occur.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Sahar Jafari, Utkarshaa Varshney, Bram Hoex, Sylke Meyer, Dominik Lausch
Summary: Hydrogen has been shown to play a significant role in light- and elevated temperature-induced degradation in silicon devices. Quantitatively assessing hydrogen in photovoltaic applications is challenging. Experiments demonstrated that the amount of hydrogen effused from silicon nitride and aluminum oxide dielectric films correlates strongly with the observed extent of LeTID in multicrystalline silicon wafers.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Nathan L. Chang, Geedhika K. Poduval, Borong Sang, Kean Khoo, Michael Woodhouse, Fred Qi, Mohammad Dehghanimadvar, Wei Min Li, Renate J. Egan, Bram Hoex
Summary: The production cost of using atomic layer deposition (ALD) to form transition metal oxide (TMO) layers as alternatives to commonly used layers in HJT solar cells (p-doped, n-doped, and indium tin oxide) is likely to be lower than the standard HJT. The main cost driver is the cost of the ALD precursors. This study motivates further development of ALD TMO processes to increase their efficiency and take advantage of the cost advantage.
PROGRESS IN PHOTOVOLTAICS
(2023)
Article
Energy & Fuels
Shaozhou Wang, Giuseppe Scardera, Fa-Jun Ma, Yu Zhang, David Payne, Malcolm Abbott, Bram Hoex
Summary: Nanostructured black silicon surfaces show promise for silicon solar cells. However, developing high-efficiency black silicon solar cells is challenging due to the inferior electrical performance of the black silicon emitters. This article investigates the effect of surface nanofeature sizes on the performance of black silicon emitters.
IEEE JOURNAL OF PHOTOVOLTAICS
(2022)
Article
Nanoscience & Nanotechnology
Shaozhou Wang, Tong Xie, Ran Liang, Yu Zhang, Fa-Jun Ma, David Payne, Giuseppe Scardera, Bram Hoex
Summary: The study utilizes artificial intelligence methods to compile a comprehensive evaluation of the performance of black silicon solar cells, finding that the weighted average reflectance is an effective surface metric and demonstrating the potential of black silicon nanotextures for improving solar cell efficiency.
ACS APPLIED NANO MATERIALS
(2022)
Review
Green & Sustainable Science & Technology
Seyyed Ali Sadat, Bram Hoex, Joshua M. Pearce
Summary: This review examines the effects of haze on solar photovoltaic (PV) performance and identifies research gaps. Haze reduces irradiance and changes the solar spectrum, affecting PV materials differently. Haze also impacts revenue loss for PV operators and requires customized PV systems. Air pollution control regulations and international actions are necessary to increase global PV output.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
(2022)
Article
Materials Science, Multidisciplinary
Yu Zhang, Giuseppe Scardera, Shaozhou Wang, Malcolm Abbott, David Payne, Bram Hoex
Summary: Phosphorous dopant diffusion profiles are important in many silicon semiconductor devices, and accurate spatially resolved dopant profiling is crucial for understanding their performance. The scanning electron microscopy for dopant contrast imaging (SEMDCI) method is effective in obtaining these profiles, especially for silicon samples with surface nanotexturing or black silicon (BSi) technology. However, previous studies have shown a poor correlation between the dopant concentration and the secondary electron (SE) signal contrast. This work presents improvements in contrast, correlation, and image condition normalization, and applies the SEMDCI method for the first time to obtain 2D electron concentration maps for planar and BSi samples.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Materials Science, Multidisciplinary
Xin Cui, Kaiwen Sun, Jialiang Huang, Heng Sun, Ao Wang, Xiaojie Yuan, Martin Green, Bram Hoex, Xiaojing Hao
Summary: Cu2ZnSnS4 (CZTS) solar cells are promising due to their abundance, dry processability, and environmental friendliness. This study demonstrates the deposition of a ZnMgO window layer using atomic layer deposition (ALD), which exhibits superior smoothness and suitable doping density. The optimized ZnMgO layer reduces charge carrier recombination and parasitic absorption, leading to improved voltage and current characteristics of the CZTS solar cell, with an efficiency of 10%.
ACS MATERIALS LETTERS
(2023)
Article
Energy & Fuels
Chandany Sen, Xinyuan Wu, Haoran Wang, Muhammad Umair Khan, Lizhong Mao, Fangdan Jiang, Tao Xu, Guangchun Zhang, Catherine Chan, Bram Hoex
Summary: Bifacial passivated emitter and rear cells (PERC) currently dominate the photovoltaic market, but heterojunction (HJT) and tunnel oxide passivated contact (TOPCon) solar cells are expected to gain significant market share. This study investigates the impact of sodium chloride (NaCl) on damp-heat-induced degradation in these cell technologies and finds that TOPCon cells degrade the most, followed by HJT and PERC cells. The increase in degradation is attributed to corrosion of the metal contact, caused by Na+ and Cl- ions penetrating the contact. These findings are important for understanding the potential failures in the field.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)