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Nanophotonic energy storage in upconversion nanoparticles
摘要： In nanophotonic energy storage, an energy conversion model is established for intrinsic nanophotonic energy storage (NPES) effects. Here we realize that the charge inhomogeneous distribution on the surface of upconversion nanoparticles (UCNPs) would persistently exist as well as the formation and migration of surface defects states despite of the compound component ratio, even following the stringent stoichiometric ratio. Our preliminary efforts on NPES effect has recognized from the recent published work [Nature 561, 88 (2018)], which the surface quantum confinement arose because of a recently found surface vacancy induced Coulomb states (SVIC) states. Further in-depth excavation on surface charge density distributions and defect orbitals of surface localized electronics and holes have affirmatively repeated the Guerra’s theory [Nature 554, 346 (2018)] and reflected the existence of surface defect states in both stoichiometric and non-stoichiometric compounds. Therefore, beyond the experimental trail-based multi-doping chemical modifications, we proposed the surface electronic process for efficient NPES effect can be modulated by an intrinsic level-matching induced surface resonant quantum tunneling (LM-SRQT) in this work. The UCNP size-effect can be confirmed that simply might be not an influencing factor of dominating NPES effect while the surface degree of non-crystallizations indeed matters.
关键词： level-matching induced surface resonant quantum tunneling (LM-SRQT),surface vacancy induced Coulomb states (SVIC) states,nano energy,nanophotonic energy storage (NPES),electron-transfer surface mechanism
更新于2025-09-23 15:21:21
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[Texts and Readings in Physical Sciences] Open Quantum Systems Volume 20 (Dynamics of Nonclassical Evolution) || Quantum Tunneling
摘要： Tunneling is a bona?de quantum mechanical e?ect [175, 176]. Since it involves barrier penetration, it is also an inherently non-perturbative process. It serves a crucial role in the test of quantum coherence in macroscopic regimes, also known as Macroscopic Quantum Coherence (MQC) [68]. Development in technology has made the concept of tunneling crucial to the development of devices on the nanoscopic, nanometre 10?9m range, and mesoscopic, upto a few microns μm, scales. Further, tunneling has important rami?cations to almost all branches of physics, such as atomic, molecular, condensed matter physics as well as to quantum ?eld theory and cosmology. A very powerful technique for dealing with tunneling is the semiclassical approximation, which we detail below. Tunneling processes can be broadly classi?ed into two categories: coherent and incoherent tunneling. Coherent tunneling phenomena involve the coherent overlap of wavefunctions located in individual domains, such as, ground states of potential wells, and separated by energy barriers. Incoherent tunneling involves scattering between reservoirs or decay of metastable states into the continuum and hence no overlap of the wavefunction. Tunneling has two perspectives: time independent energy domain considerations and that invoking the time dependent dynamics.
关键词： Macroscopic Quantum Coherence,Semiclassical Approximation,Quantum Tunneling,Incoherent Tunneling,Coherent Tunneling
更新于2025-09-23 15:21:01
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Development and Study of the pa??ia??n GaAs/AlGaAs Tunnel Diodes for Multijunction Converters of High-Power Laser Radiation
摘要： The creation of connecting tunnel diodes with a peak tunneling-current density higher than the density of the short-circuit current of photoactive p–n junctions is an important task in the development of multijunction photoconverters (III–V) of high-power optical radiation. Basing on numerical simulation of the J–U characteristics of tunnel diodes, a method is proposed for increasing the peak tunneling-current density by including a thin undoped i-type layer with a thickness of several nanometers between degenerate layers of the tunnel diode. The p–i–n-GaAs/Al0.2Ga0.8As structures of the connecting tunnel diodes with a peak tunneling-current density of up to 200 A/cm2 are grown by molecular-beam epitaxy.
关键词： quantum tunneling,molecular-beam epitaxy,tunnel diode,multijunction photoconverter,current–voltage characteristic
更新于2025-09-23 15:21:01
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Light from van der Waals quantum tunneling devices
摘要： The understanding of and control over light emission from quantum tunneling has challenged researchers for more than four decades due to the intricate interplay of electrical and optical properties in atomic scale volumes. Here we introduce a device architecture that allows for the disentanglement of electronic and photonic pathways—van der Waals quantum tunneling devices. The electronic properties are defined by a stack of two-dimensional atomic crystals whereas the optical properties are controlled via an external photonic architecture. In van der Waals heterostructures made of gold, hexagonal boron nitride and graphene we find that inelastic tunneling results in the emission of photons and surface plasmon polaritons. By coupling these heterostructures to optical nanocube antennas we achieve resonant enhancement of the photon emission rate in narrow frequency bands by four orders of magnitude. Our results lead the way towards a new generation of nanophotonic devices that are driven by quantum tunneling.
关键词： van der Waals heterostructures,inelastic electron tunneling,nanophotonics,light emission,quantum tunneling,optical antennas
更新于2025-09-19 17:15:36
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Van der Waals broken-gap p-n heterojunction tunnel diode based on black phosphorus and rhenium disulfide
摘要： The broken-gap type-III van der Waals (vdW) heterojunction is of particular interest as there is no overlap between the energy bands of its two stacked materials. Despite several studies on straddling-gap (type-I) and staggered-gap (type-II) vdW heterojunctions, a comprehensive understanding of the current-transport and optoelectronic effects in a type-III broken-gap heterojunction remains elusive. Here, we report gate-tunable current rectifying characteristics in a black phosphorus (BP)/rhenium disulfide (ReS2) broken-gap p-n heterojunction diode. Current-transport in this heterojunction was modeled by using the Simmons approximation through direct tunneling and Fowler?Nordheim tunneling in low- and higher-bias regimes, respectively. We showed that a p-n diode based on a type-III heterojunction is mainly governed by tunneling-mediated transport, but that transport in a type-I p-n heterojunction is dominated by majority carrier diffusion in the higher-bias regime. Upon illumination with a 532-nm-wavelength laser, the BP/ReS2 broken-gap p-n heterojunction showed a photo responsivity of 8 mA/W at a laser power as high as 100 μW and photovoltaic energy conversion with an external peak quantum efficiency of 0.3%. Finally, we demonstrated a binary inverter consisting of BP p-channel and ReS2 n-channel thin film transistors for logic applications.
关键词： Rhenium disulfide,photovoltaics,quantum tunneling,broken-gap heterojunction,logic circuitry,Black phosphorous
更新于2025-09-19 17:15:36
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Quantum behavior of hydrogen-vacancy complexes in diamond
摘要： Hydrogen plays an essential role in the growth process of artificial diamond and can easily form complexes with lattice vacancies. Despite substantial efforts to resolve the electronic structure and the ground-state properties of the hydrogen-vacancy (HV) center, the final remarks are ambiguous, while the complexes of vacancy with two and more hydrogen atoms remain unexplored. In this paper, we used spin-polarized, hybrid density-functional theory method to investigate electronic structure and magneto-optical properties of various hydrogen-vacancy clusters in diamond. Our theoretical results indicate a very strong tendency toward the formation of HnV complexes up to four hydrogen atoms that are mostly electrically and optically active centers. One of the investigated defects introduce highly correlated electronic states that pose a challenge for density-functional theory and, therefore, require special treatment when charge- and spin-density-related properties are determined. We introduced an extended Hubbard model Hamiltonian with fully ab initio provided parameters to analyze the complex electronic structure of highly correlated H2V0 defects. The role of quantum tunneling of hydrogen in HV center and its impact on the hyperfine structure was discussed. We demonstrate that experimentally observed HV1? center is similar to well-known NV1?, i.e., I) it possesses triplet 3A ground state and 3E excited state in C3v symmetry; II) the calculated zero-phonon line is 1.71 eV (1.945 eV for NV1?). A detailed experimental reinvestigation based on optically detected electron paramagnetic resonance spectroscopy is suggested to verify whether the HV1? center has metastable singlet shelving states between the ground and excited state triplets and, as a result, whether it may exhibit a spin-selective decay to the ground state.
关键词： quantum tunneling,diamond,hydrogen-vacancy complexes,magneto-optical properties,density-functional theory,quantum behavior
更新于2025-09-09 09:28:46
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Solution of the time dependent Schr?dinger equation leading to Fowler-Nordheim field emission
摘要： We solve the time-dependent Schr?dinger equation describing the emission of electrons from a metal surface by an external electric field E, turned on at t = 0. Starting with a wave function ψ(x, 0), representing a generalized eigenfunction when E = 0, we find ψ(x, t) and show that it approaches, as t → ∞, the Fowler-Nordheim tunneling wavefunction ψE(x). The deviation of ψ from ψE decays asymptotically as a power law t?3. The time scales involved for typical metals and fields of several V/nm are of the order of femtoseconds. We plot the short-time evolution of the current and density.
关键词： electron emission,time-dependent Schr?dinger equation,Fowler-Nordheim field emission,quantum tunneling
更新于2025-09-09 09:28:46
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Ultimate limit in size and performance of WSe2 vertical diodes
摘要： Precise doping-profile engineering in van der Waals heterostructures is a key element to promote optimal device performance in various electrical and optical applications with two-dimensional layered materials. Here, we report tungsten diselenide- (WSe2) based pure vertical diodes with atomically defined p-, i- and n-channel regions. Externally modulated p- and n-doped layers are respectively formed on the bottom and the top facets of WSe2 single crystals by direct evaporations of high and low work-function metals platinum and gadolinium, thus forming atomically sharp p–i–n heterojunctions in the homogeneous WSe2 layers. As the number of layers increases, charge transport through the vertical WSe2 p–i–n heterojunctions is characterized by a series of quantum tunneling events; direct tunneling, Fowler–Nordheim tunneling, and Schottky emission tunneling. With optimally selected WSe2 thickness, our vertical heterojunctions show superb diode characteristics of an unprecedentedly high current density and low turn-on voltages while maintaining good current rectification.
关键词： current rectification,WSe2,van der Waals heterostructures,quantum tunneling,vertical diodes
更新于2025-09-04 15:30:14