- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Towards Free Standing Lonsdaleite and Diamond Few Layers: The Nitrogen Effect
摘要： Strong, directional, N bonding led surface stabilization is induced to obtain free standing two dimensional layered assemblies of Lonsdaleite and diamond phase carbon by surface termination at 3 coordinated C sites. These assemblies have strong bonding and surface N lone pair induced self protection and achieves respective bulk-like electronic, mechanical and crystallographic properties at as low as 7 atomic layer thickness. Lonsdaleite phase sub-nano thickness free standing as small as 3 layered assembly shows bulk-like thermal stability up to 2900K. Size con?nement e?ect dominates up to four layered assembly and then electronic and crystallographic properties are dominated by bulk stabilization which saturates towards respective bulk-like features from 7 layer assembly. Similarly, free standing hybrid assemblies of Lonsdaleite phase carbon with BeF (C5NBeF) and BS (C5NBS) layer are also proposed along with low symmetric Cm-C3N4 layered assembly. The combination of N and O is shown to stabilize surface of nanodiamond but shows signi?cant variation in structural and electronic properties, which are principally govern by con?nement e?ect because of weak surface stabilization. Our results proposes that, in principle, two dimensional free standing layered assemblies of the sp3 hybridized phases of carbon with surface terminated by only 3 coordinated C sites, can be stabilized and engineered by substitutional doping of N, and in some cases respective bulk-like electronic and crystallographic properties at nano size can be achieved.
关键词： diamond,nitrogen effect,Lonsdaleite,surface stabilization,free standing layered assemblies,bulk-like properties
更新于2025-09-04 15:30:14
-
Empirical modeling of dopability in diamond-like semiconductors
摘要： Carrier concentration optimization has been an enduring challenge when developing newly discovered semiconductors for applications (e.g., thermoelectrics, transparent conductors, photovoltaics). This barrier has been particularly pernicious in the realm of high-throughput property prediction, where the carrier concentration is often assumed to be a free parameter and the limits are not predicted due to the high computational cost. In this work, we explore the application of machine learning for high-throughput carrier concentration range prediction. Bounding the model within diamond-like semiconductors, the learning set was developed from experimental carrier concentration data on 127 compounds ranging from unary to quaternary. The data were analyzed using various statistical and machine learning methods. Accurate predictions of carrier concentration ranges in diamond-like semiconductors are made within approximately one order of magnitude on average across both p- and n-type dopability. The model fit to empirical data is analyzed to understand what drives trends in carrier concentration and compared with previous computational efforts. Finally, dopability predictions from this model are combined with high-throughput quality factor predictions to identify promising thermoelectric materials.
关键词： dopability,machine learning,diamond-like semiconductors,thermoelectrics,carrier concentration
更新于2025-09-04 15:30:14
-
Imaging the Local Charge Environment of Nitrogen-Vacancy Centers in Diamond
摘要： Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields, and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we demonstrate that local electric fields dominate the magnetic resonance behavior of NV ensembles at a low magnetic field. We introduce a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning more than two orders of magnitude. Motivated by this understanding, we propose and implement a novel method for the nanoscale localization of individual charges within the diamond lattice; our approach relies upon the fact that the charge induces a NV dark state which depends on the electric field orientation.
关键词： diamond,local electric fields,nanoscale localization,nitrogen-vacancy center,magnetic resonance
更新于2025-09-04 15:30:14
-
Detection of high flux synchrotron radiation based on diamond detector for HEPS
摘要： High Energy Photon Source (HEPS) with a beam energy of 6 GeV and emittance less than 1.0 nm rad will be constructed in China, which can provide high-brightness hard X-ray in the order of 1022 (phs/s/mm2/mr2/0.1%B.W.). The broadband and high-brightness monochromatic beam flux and white beam flux need new detector other than the ion chambers for measurement in case of saturation under high-flux conditions. The Diamond X-ray detector for the beam position monitoring and high brightness X-ray detection is developing for High Energy Photon Source in China. The diamond detector has advantages over other detector materials: a low atomic number resulting in a low absorption cross-section when used as beam position monitor and a high radiation and wide linear range when used as beam intensity measuring. In this paper, the polycrystalline chemical-vapour-deposition diamond detectors with an aluminium contact have been tested at 1W2B beamline at Beijing Synchrotron Radiation Facility (BSRF). A transmission-mode diamond X-ray detector is designed to simultaneously measure the X-ray flux, beam position in real time.
关键词： HEPS,High brightness synchrotron radiation,Beam position,Diamond detector
更新于2025-09-04 15:30:14
-
3.8 W/mm power density for ALD Al2 O 3 -based two-dimensional hole gas diamond MOSFET operating at saturation velocity
摘要： This paper reports large-signal performances at high drain voltage (VDS) ranging up to 60 V for a 0.5 μm gate diamond (2DHG) metal-oxide-semiconductor transistor (MOSFET) with a 100-nm-thick atomic-layer-deposited (ALD) Al2O3 film on a IIa-type polycrystalline diamond substrate with a (110) preferential surface. This diamond FET demonstrated a cutoff frequency (fT) of 31 GHz, indicating that its carrier velocity was reaching 1.0×107 cm/s for the first time in diamond. In addition, a fT of 24 GHz was obtained at VDS = ?60 V, thus giving a fT × VDS product of 1.44 THz·V. This diamond FET is promising for use as a high-frequency transistor under high voltage conditions. Under application of a high voltage, a maximum output power density of 3.8 W/mm (the highest in diamond) with an associated gain and power added efficiency were 11.6 dB and 23.1% was obtained when biased at VDS = ?50 V using a load-pull system at 1GHz.
关键词： high frequency,Diamond,output power,high voltage,MOSFET
更新于2025-09-04 15:30:14
-
Monoisotopic Ensembles of Silicon-Vacancy Color Centers with Narrow-Line Luminescence in Homoepitaxial Diamond Layers Grown in H <sub/>2</sub> –CH <sub/>4</sub> – <sup> [ <i>x</i> ] </sup> SiH <sub/>4</sub> Gas Mixtures ( <i>x</i> = 28, 29, 30)
摘要： Silicon-vacancy (SiV?) color center in diamond is of high interest for applications in nanophotonics and quantum information technologies, as a single photon emitter with excellent spectral properties. To obtain spectrally identical SiV? emitters, we doped homoepitaxial diamond ?lms in situ with 28Si, 29Si, and 30Si isotopes using isotopically enriched (>99.9%) silane SiH4 gas added in H2?CH4 mixtures in the course of the microwave plasma-assisted chemical vapor deposition process. Zero-phonon line components as narrow as ～4.8 GHz were measured in both absorption and luminescence spectra for the monoisotopic SiV? ensembles with a concentration of a few parts per billion. We determined with high accuracy the Si isotopic energy shift of SiV? zero-phonon line. The SiV? emission intensity is shown to be easily controlled by the doped epi?lm thickness. Also, we identi?ed and characterized the localized single photon SiV? sources. The developed doping process opens a way to produce the SiV? emitter ensembles with energy con?ned in an extremely narrow range.
关键词： diamond,silicon-vacancy center,CVD synthesis,optical absorption,photoluminescence,doping,silicon isotope
更新于2025-09-04 15:30:14