Boron nitride (BN) is primarily a synthetically produced advanced ceramic material. It is isoelectronic to carbon and, like carbon, can exist as several polymorphic modifications. Microwave plasma chemical vapor deposition (MPCVD) of metastable wurtzite boron nitride is reported for the first time and found to be facilitated by the application of direct current (DC) bias to the substrate. The applied negative DC bias was found to yield a higher content of bonded BN in both cubic and metastable wurtzite structural forms. This is confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Nano-indentation measurements reveal an average coating hardness of 25 GPa with some measurements as high as 31 GPa, consistent with a substantial fraction of bonding mixed with the hexagonal bonded BN phase.
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http://dx.doi.org/10.3390/ma14237167 | DOI Listing |
ACS Nano
December 2024
Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
With reduced dimensionality and a high surface area-to-volume ratio, two-dimensional (2D) semiconductors exhibit intriguing electronic properties that are exceptionally sensitive to surrounding environments, including directly interfacing gate dielectrics. These influences are tightly correlated to their inherent behavior, making it critical to examine when extrinsic charge carriers are intentionally introduced to the channel for complementary functionality. This study explores the physical origin of the competitive transition between intrinsic and extrinsic charge carrier conduction in extrinsically -doped MoS, highlighting the central role of interactions of the channel with amorphous gate dielectrics.
View Article and Find Full Text PDFiScience
December 2024
Center for Reproductive Medicine and Obstetrics & Gynecology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China.
Thermodynamic theory suggests that the obvious mechanical behavior caused by temperature and interlayer angle will affect the physical properties of materials, such as mechanical properties and transportation behavior, and it is different from the behavior in three-dimensional bulk materials. We observe an abnormal physical effect of bilayer graphene/hexagonal boron nitride (G/BN)-carbon nanotube (CNT) heterostructures, with a normalized out-of-plane deformation and normalized bond angle percentage to almost several times higher those of pristine G/BN heterostructures (without CNT) at 700-800 K. Our combined finite element theory and molecular dynamics simulations confirmed that the combination of CNT and interlayer angle diverted and bridged the propagating crack and provided a stable crack propagation path and crack tip opening displacement, resulting in the stress fields to be controlled around the CNT at high temperature.
View Article and Find Full Text PDFNanoscale
December 2024
University of Warsaw, Faculty of Physics, Pasteura 5, 02-093 Warsaw, Poland.
Raman spectroscopy is a powerful analytical method widely used in many fields of science and applications. However, one of the inherent issues of this method is a low signal-to-noise ratio for ultrathin and two-dimensional (2D) materials. To overcome this problem, techniques like surface-enhanced Raman spectroscopy (SERS) that rely on nanometer scale metallic particles are commonly employed.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Department of Industrial and Materials Science, Chalmers University of Technology, Göteborg, 41296, Sweden.
Thermal conductivity enhancement in polymers is vital for advanced applications. This study introduces a novel method to align hexagonal boron nitride (hBN) nanosheets within polydimethylsiloxane (PDMS) matrices using a Halbach array to create a highly uniform magnetic field. This technique achieves significant improvements in thermal conductivity by effectively aligning hBN nanosheets.
View Article and Find Full Text PDFAdv Mater
December 2024
School of Electronic Science and Engineering, College of Engineering and Applied Sciences, National Laboratory of Solid-State Microstructures, and Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing, 210023, China.
2D transition-metal dichalcogenide (TMDC) semiconductors represent the most promising channel materials for post-silicon microelectronics due to their unique structure and electronic properties. However, it remains challenging to synthesize wide-bandgap TMDCs monolayers featuring large areas and high performance simultaneously. Herein, highly oriented WS monolayers are reproducibly synthesized through a templated growth strategy on vicinal C/A-plane sapphire wafers.
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