Article
Nanoscience & Nanotechnology
Lama Khalil, Debora Pierucci, Emilio Velez-Fort, Jose Avila, Celine Vergnaud, Pavel Dudin, Fabrice Oehler, Julien Chaste, Matthieu Jamet, Emmanuel Lhuillier, Marco Pala, Abdelkarim Ouerghi
Summary: This study visualizes the presence of a flat band near the Fermi level in the van der Waals WSe2/MoSe2 heterobilayer and confirms the coexistence of different domains with arbitrary twist angles. The strong interlayer hybridization effects are observed, which are further confirmed by complementary micro-Raman spectroscopy measurements.
Article
Engineering, Electrical & Electronic
Lu Zhang, Yadong Zhang, Xiaoting Sun, Kunpeng Jia, Qingzhu Zhang, Zhenhua Wu, Huaxiang Yin
Summary: Using metals with different work functions, such as Pd, Pt, and Ag, as contacts for WSe2 can decrease the contact resistance and potentially improve transistor performance. Optimized p-type multilayer WSe2 FETs with Pd contacts have been successfully fabricated, demonstrating excellent electrical characteristics and confirming the potential of TMD FETs in future low-power CMOS digital circuit applications.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2021)
Article
Physics, Applied
Salvatore Timpa, Mehrdad Rahimi, Jacko Rastikian, Stephan Suffit, Francois Mallet, Philippe Lafarge, Clement Barraud, Maria Luisa Della Rocca
Summary: Transition metal dichalcogenides have emerged as a platform for energy conversion solutions at the nanoscale. The electric and thermoelectric properties of devices based on two-dimensional materials are influenced by metal contacts, with different metals leading to varied Seebeck response and electrical conductivity. It is important to engineer metal contacts to optimize the thermoelectric performances of transition metal dichalcogenides based transistors.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Victoria Chen, Hye Ryoung Lee, Cagil Koroglu, Connor J. McClellan, Alwin Daus, Eric Pop
Summary: In this study, we characterized the electrical and thermoelectric properties of layered WSe2 with thicknesses ranging from 10 to 96 nm at temperatures between 300 and 400 K. By electrostatically gating the devices with an ion gel, we were able to investigate both electron and hole behavior over a wide range of carrier densities. The highest n- and p-type Seebeck coefficients for thin-film WSe2 at room temperature, -500 and 950 μV/K respectively, were obtained in this study. We also highlighted the significance of low substrate thermal conductivity for lateral thermoelectric measurements, which improves the platform for future studies on other nanomaterials.
Article
Thermodynamics
Yifeng Ling, Guojuan Qiu, Duo Liu, Erbiao Min, Jianghe Feng, Juan Li, Ping Zhang, Rong Sun, Ruiheng Liu
Summary: The thermoelectric transient supercooling is expected to suppress temperature rise in electronic devices, and the power factor has a significant impact on the response time and overshoot temperature. Both thermal contact resistance (TCR) and electrical contact resistance (ECR) negatively affect transient supercooling, with ECR having a worse effect. In addition, the interface resistance between semiconductors and metal also plays a crucial role in transient supercooling.
APPLIED THERMAL ENGINEERING
(2023)
Article
Chemistry, Multidisciplinary
Kwan-Ho Kim, Maksim Andreev, Soodon Choi, Jaewoo Shim, Hogeun Ahn, Jason Lynch, Taeran Lee, Jaehyeong Lee, Koosha Nassiri Nazif, Aravindh Kumar, Pawan Kumar, Hyongsuk Choo, Deep Jariwala, Krishna C. Saraswat, Jin-Hong Park
Summary: Global energy consumption is increasing rapidly, leading to a higher demand for renewable energy. Van der Waals materials have recently been identified as efficient absorbers for thin and highly efficient photovoltaic devices. Researchers have achieved a significant improvement in power conversion efficiency in van der Waals-based photovoltaic devices by introducing a tungsten oxide layer and monolayer graphene.
Article
Chemistry, Physical
G. Alba, D. Leinen, M. P. Villar, R. Alcantara, J. C. Pinero, A. Fiori, T. Teraji, D. Araujo
Summary: This study analyzed the WC/O-diamond interface annealed at 600K for the first time, revealing the presence of a metastable cubic-WC phase and interface oxygen. The Schottky Barrier Height of the WC/O-diamond contact was estimated at 1.6 +/- 0.2 eV, consistent with I/V measurements.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Rahul, Sunil K. Arora, S. N. Jha, Yogesh Kumar
Summary: In this work, the band alignment of few-layer thick WSe2/SiO2 heterointerface was studied using various experimental techniques, and the specific valence band and conduction band offset values were calculated.
Article
Nanoscience & Nanotechnology
Xinglu Wang, Seong Yeoul Kim, Robert M. Wallace
Summary: The high contact resistance of transition-metal dichalcogenide (TMD)-based devices is a limiting factor for their application. The study on the interface chemistry and band alignment of metal/MoS2 shows that Ni forms a covalent contact while Ag forms van der Waals gaps, with potential for Ag to form an Ohmic contact on MoS2 bulk.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Physics, Applied
Cunyuan Jiang, Zhiyao Yang, Wen Xiong, Fei Wang
Summary: In this study, it was found that biaxial and uniaxial tensile strains within the range of 0%-6% have a similar effect on magnetism-induced valley splitting in WSe2/CrSe2 heterojunction. However, at larger magnitudes of 6%-10%, uniaxial strain dramatically decreases the valley splitting, which can be attributed to different spin splitting induced by spin-orbit coupling between the two valleys.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Jiaqi Chen, Zhaofu Zhang, Yuzheng Guo, John Robertson
Summary: The rational design of metal contacts on transition metal dichalcogenides can significantly improve the performance of 2D devices. Previous research has shown that Moire interfaces enhance the stability of interface sites and enable easier variation of the Schottky barrier height. This study extends the calculations to p-type and ambipolar WSe2 contacts.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Peiyu Qiao, Jing Xia, Xuanze Li, Yuye Li, Jianyu Cao, Zhongshi Zhang, Heng Lu, Qing Meng, Jiangtao Li, Xiang-Min Meng
Summary: In this study, a two-step chemical vapor deposition (CVD) growth method was used to prepare 2D TaSe2-WSe2 metal-semiconductor heterostructures. The results show that these heterostructures can improve the performance of electrical devices and have potential applications in future high-performance integrated circuits.
Article
Nanoscience & Nanotechnology
Sisi Guo, Qiufeng Meng, Jie Qin, Yong Du, Lei Wang, Per Eklund, Arnaud le Febvrier
Summary: Conducting polymer poly(3,4-ethylenedioxythiophene) nanowires (PEDOTNWs) were synthesized and self-supporting exfoliated WSe2-nanosheet (NS)/PEDOT-NW composite films were fabricated using a modified self-assembled micellar soft-template method and vacuum filtration. Increasing the mass fractions of WSe2 NSs in the composite films led to a decrease in electrical conductivity and an increase in Seebeck coefficient. The sample containing 5 wt % WSe2 NSs achieved the highest room-temperature power factor and exhibited mechanical flexibility. Furthermore, a flexible thermoelectric power generator using this composite material demonstrated high power density.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
B. Jayachandran, B. Prasanth, R. Gopalan, T. Dasgupta, D. Sivaprahasam
Summary: This study successfully fabricated thermally stable Cu/Mg2Si0.4Sn0.6 joints using an SS304 interlayer in a single-step process, preventing an increase in electrical resistivity due to Cu diffusion and maintaining low specific contact resistance.
MATERIALS RESEARCH BULLETIN
(2021)
Article
Physics, Multidisciplinary
Ping Tang, Ryo Iguchi, Ken-ichi Uchida, Gerrit E. W. Bauer
Summary: We present a scattering theory for polarization and heat transport in a ballistic ferroelectric point contact. We predict the presence of a polarization current under either an electric field or a temperature difference, which strongly depends on the direction of the ferroelectric order and can be detected through its magnetic stray field, thermovoltage, and Peltier effect.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Maria Gabriela Sales, Lucas Herweyer, Elizabeth Opila, Stephen McDonnell
APPLIED SURFACE SCIENCE
(2020)
Article
Chemistry, Physical
William H. Blades, Nicholas J. Frady, Peter M. Litwin, Stephen J. McDonnell, Petra Reinke
JOURNAL OF PHYSICAL CHEMISTRY C
(2020)
Article
Materials Science, Multidisciplinary
N. Liu, T. Zhu, M. G. Rosul, J. Peters, J. E. Bowers, M. Zebarjadi
MATERIALS TODAY PHYSICS
(2020)
Article
Physics, Applied
David H. Olson, Maria G. Sales, John A. Tomko, Teng-Fei Lu, Oleg V. Prezhdo, Stephen J. McDonnell, Patrick E. Hopkins
Summary: This study experimentally determined the electron-electron conductance at Au/TiOx interface regions and electron-phonon coupling of thin TiOx layers for x=0-2.62. The research found that electronic energy transport mechanisms at metal/metal oxide interfaces are enhanced through metallic defects and analyzed the processes using pump/probe technique and a two-temperature model. The results also showed that TiOx stoichiometries near TiO2 have ultrahigh electron-phonon coupling factors, and electron-phonon coupling is reduced for x=2.62 in TiOx.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Maria Gabriela Sales, Samantha T. Jaszewski, Shelby S. Fields, Peter M. Litwin, Jon F. Ihlefeld, Stephen J. McDonnell
Summary: The thermal stability of the interface between ferroelectric oxides and transition metal dichalcogenides was explored in this study, revealing variations in stability and crystallization characteristics under different conditions through XPS and XRD analysis.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Shelby S. Fields, Sean W. Smith, Chris M. Fancher, Michael David Henry, Steve L. Wolfley, Maria G. Sales, Samantha T. Jaszewski, Mark A. Rodriguez, Giovanni Esteves, Paul S. Davids, Stephen J. McDonnell, Jon F. Ihlefeld
Summary: The stability of ferroelectric phase in hafnium oxide is influenced by factors such as composition, biaxial stress, crystallite size, and oxygen vacancies. The study reveals that post-processing stress states of HZO films do not depend on the stress of the adjacent TaN electrodes, and a chemical interaction between TaN and HZO layers impacts the ferroelectric phase stability and polarization performance. It is essential to consider electrode processing and chemistry in the performance of ferroelectric hafnia films.
ADVANCED MATERIALS INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Maria Gabriela Sales, Shelby Fields, Samantha Jaszewski, Sean Smith, Takanori Mimura, Wendy L. Sarney, Sina Najmaei, Jon F. Ihlefeld, Stephen McDonnell
Summary: Direct integration of transition metal dichalcogenides on a ferroelectric HZO substrate using molecular beam epitaxy (MBE) is investigated in this study. The results show that the crystallinity and composition of the HZO substrate can affect the degree of Se incorporation. However, measurements of the electrical properties of the HZO films did not show any negative impact of the incorporated Se on the functionality of the ferroelectric layer.
Article
Chemistry, Physical
Lee Kendall, Amir Chamaani, Zachary Piontkowski, Thomas E. Beechem, Mackenzie Ridley, Elizabeth J. Opila, Giovanni Zangari, Stephen J. McDonnell
Summary: Electrocatalysts of MoOxSy synthesized by potentiostatic electrodeposition exhibit good performance for the hydrogen evolution reaction, but the presence of oxygen influences their performance. The presence of oxygen and molybdenum oxidation state can be modified by air exposure, annealing in an inert atmosphere, and annealing in a sulfur flux. Despite modified films showing worse HER performance, the importance of the Mo5+ oxidation state and the identification of an unreported state between Mo4+ and Mo5+ in MoOxSy catalysts were highlighted through extensive X-ray photoelectron spectroscopy studies.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Carol F. Glover, Tsuyoshi Miyake, Victor Wallemacq, Jamie D. Harris, John Emery, Daniel A. Engel, Stephen J. McDonnell, John R. Scully
Summary: Contamination of high-touch surfaces with infected droplets of bodily secretions is a known route of virus transmission. Copper surfaces have the ability to inactivate human coronaviruses by releasing ions, making them a potential preventive strategy. This study investigated the virus inactivation effect on copper surfaces under realistic conditions and discovered that the half-life of the virus decreased five times compared to previous knowledge, indicating that virus inactivation on copper surfaces may be more effective than previously thought.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Physics, Applied
Qi Feng, Tianhui Zhu, Yu Jian, Wei Yuan, Huimin Peng, Jinrui Zhong, Junxi Duan, Mona Zebarjadi
Summary: The study of the Nernst effect in 2D materials is significant due to the discovery of topologically nontrivial electronic band structures in 2D ferromagnets and antiferromagnets. This study demonstrates that the temperature gradient in 2D materials strongly depends on the distance from the heater, but can be accurately described by a linear function. This finding provides a precise method to measure the Nernst coefficient of 2D materials.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Tianhui Zhu, Peter M. Litwin, Md Golam Rosul, Devin Jessup, Md Sabbir Akhanda, Farjana F. Tonni, Sergiy Krylyuk, Albert Davydov, Petra Reinke, Stephen J. McDonnell, Mona Zebarjadi
Summary: 4-layer NbSe2 films were successfully grown on SiO2 using molecular beam epitaxy. The metallic nature of the samples was confirmed through experiments and theoretical calculations, with a change in the Seebeck coefficient observed at different temperatures.
MATERIALS TODAY PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Tianhui Zhu, Yunhui Wu, Shuai Li, Farjana F. Tonni, Masahiro Nomura, Mona Zebarjadi
Summary: Silicon thin films are promising for chip-integrated Peltier micro-coolers and thermoelectric power generators due to their compatibility and cost effectiveness. This study focuses on reducing thermal conductivity by creating patterned nano-holes in single crystalline silicon thin films and surface doping them with organic molecules F4TCNQ. The results show significant improvements in electrical conductivity and power factor.
MATERIALS TODAY PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Jie Zhang, Meng Jia, Maria Gabriela Sales, Yong Zhao, Guangyang Lin, Peng Cui, Chaiwarut Santiwipharat, Chaoying Ni, Stephen McDonnell, Yuping Zeng
Summary: This study systematically investigates the impact of ZrO2 gate dielectric thickness on the electrical performance of TiO2 thin film transistors. It is found that a 5 nm-thick ZrO2 dielectric can significantly enhance the electrical performance of TiO2 TFTs, making them suitable for Internet of Things applications.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
