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Analytic Model of Spalling Technique for Thickness-Controlled Separation of Single-Crystalline Semiconductor Layers
摘要： Thickness-controlled separation of a thin layer of single-crystalline semiconductors from its bulk substrate is being developed for co-integration of compound semiconductors with silicon-based integrated-circuit (IC) chips and fabrication of high-performance flexible devices. Recently, a controlled spalling technique that can mechanically separate single-crystalline semiconductor layers has been actively demonstrated because of the process simplicity and the less limitation in materials. Here, we developed an analytic model that can precisely estimate the spalling depth. In this model, the spalling depth was calculated from the thermodynamic equilibrium condition in which total strain energy accumlated in a separated layer is balanced with the crystal binding energy. We empirically investigated the dependence of the spalling depth on the stressor layer thickness and stress, and we compared the empirical results with the suggested analytic model. We also verified that the crack initiation angle of the spalling process is determined by the binding energy contrast in the main crystal orientations in the semiconductor.
关键词： thermodynamic equilibrium condition,analytic model,spalling technique,thickness-controlled layer separation,crack initiation angle
更新于2025-09-12 10:27:22
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European Microscopy Congress 2016: Proceedings || Structural transformations revealed by in-situ HRTEM observations
摘要： With the recent advance of In-Situ Transmission Electron Microscopy (In-Situ TEM), it has become a very essential technique to understand the structure-property relationships of materials. Here, we demonstrate that the formation mechanism of 1D-Si nanowires is initiated by the atom intrusion into the Si lattice at the interfaces, and the formation process is advanced by the atom intrusion into the Si lattice at the interfaces. The formation mechanism of 1D-Si nanowires is also discussed by the thermodynamic analysis. It is found that the 1D-Si nanowires are formed at the triple junction at the interfaces, and the formation process is advanced by the atom intrusion into the Si lattice at the interfaces. The formation mechanism of 1D-Si nanowires is also discussed by the thermodynamic analysis.
关键词： formation mechanism,atom intrusion,In-Situ TEM,thermodynamic analysis,1D-Si nanowires
更新于2025-09-11 14:15:04
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Boosting the ultra-stable unencapsulated perovskite solar cells by using montmorillonite/CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> nanocomposite as photoactive layer
摘要： Lead halide perovskites, such as methylammonium lead iodide (MAPbI3) can reach near 100% internal quantum e?ciency in single solar cells, but they still encounter significant thermodynamic losses in photon energy to o?set device photovoltage and performance. Herein, a novel prismatic perovskite solar cell with light trapping configuration, namely, Prim PVSC, is designed to mitigate such losses in devices, through modulating the pathway of light inside series cells, wherein incident high-to-low energy photons are separately captured by four horizontally aligned MAPbIxBr3?x subcells with varied bandgaps. This newly designed PVSC has remarkably led to a record open circuit voltage of 5.3 V in four series devices and power conversion e?ciency of 21.3%, which could provide a new way to break the performance bottleneck of perovskites. Practically, this type of device architecture could also be applied in flexible modules for large-area application.
关键词： perovskite solar cells,light trapping,photovoltage,thermodynamic losses,power conversion efficiency
更新于2025-09-11 14:15:04
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Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation
摘要： Graphene has long been predicted to show exceptional nonlinear optical properties, especially in the technologically important terahertz (THz) frequency range. Recent experiments have shown that this atomically thin material indeed exhibits possibly the largest nonlinear coefficients of any material known to date, paving the way for practical graphene-based applications in ultrafast (opto-)electronics operating at THz rates. Here the advances in the booming field of nonlinear THz optics of graphene are reported, and the state-of-the-art understanding of the nature of the nonlinear interaction of graphene with the THz fields based on the thermodynamic model of electron transport in graphene is described. A comparison between different mechanisms of nonlinear interaction of graphene with light fields in THz, infrared, and visible frequency ranges is also provided. Finally, the perspectives for the expected technological applications of graphene based on its extraordinary THz nonlinear properties are summarized. This report covers the evolution of the field of THz nonlinear optics of graphene from the very pioneering to the state-of-the-art works. It also serves as a concise overview of the current understanding of THz nonlinear optics of graphene and as a compact reference for researchers entering the field, as well as for the technology developers.
关键词： terahertz,high-harmonics generation,nonlinear optics,thermodynamic model,graphene
更新于2025-09-11 14:15:04
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Effect of confinement potential shape on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot at finite temperature
摘要： The effect of the shape of the confinement potential on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot is studied using the power-exponential potential model with steepness parameter p. The average energy, heat capacity, magnetic susceptibility and persistent current are calculated using the canonical ensemble approach at low temperature. It is shown that for soft confinement, the average energy depends strongly on p while it is almost independent of p for hard confinement. The heat capacity is found to be independent of the shape and depth of the confinement potential at low temperatures and for the magnetic field considered. It is shown that the system undergoes a paramagnetic-diamagnetic transition at a critical value of the magnetic field. It is furthermore shown that for low values of the potential depth, the system is always diamagnetic irrespective of the shape of the potential if the magnetic field exceeds a certain value. For a range of the magnetic field, there exists a window of p values in which a re-entrant behavior into the diamagnetic phase can occur. Finally, it is shown that the persistent current in the present quantum dot is diamagnetic in nature and its magnitude increases with the depth of the dot potential but is independent of p for the parameters considered.
关键词： transport properties,thermodynamic properties,canonical ensemble approach,electronic properties,quantum dot,GaAs,paramagnetic-diamagnetic transition,persistent current,magnetic properties,power-exponential potential model,confinement potential
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Microwave Method for Closure of Quasi-Spherical Resonator
摘要： Quasi-spherical microwave cavity resonators are widely used in primary thermometry. To realize high-accuracy microwave resonant frequency measurement, it is essential to close the two quasi-hemispheres correctly. We show how to do this using microwave resonance signals to monitor shape and sealing as torques to equatorial bolts are increased. The present resonator was closed with torques up to 105 cNm. The method should be useful to monitor the closing of other quasi-spherical cavities.
关键词： Quasi-spherical cavity,Resonant frequency,Thermometry,Microwave measurement,Thermodynamic temperature
更新于2025-09-10 09:29:36
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NBO, nonlinear optical and thermodynamic properties of 10-Acetyl-10H-phenothiazine 5-oxide
摘要： In this paper, natural bond orbital (NBO) analysis, nonlinear optical and the thermodynamic properties of 10-Acetyl-10H-phenothiazine 5-oxide have been analyzed by employing density functional theory level employing 6-311++G(d,p) basis set. NBO analysis reveals that the intra- intermolecular charge transfer occurs within the molecule leading to the stabilization. The predicted nonlinear optical properties (NLO) like; polarizability and first hyperpolarizabiliy support that the molecule could attract the interests for future investigation.
关键词： DFT,Nonlinear optical and thermodynamic properties.,NBO,APTZ
更新于2025-09-10 09:29:36
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Structural, elastic, electronic, thermodynamic, and optical properties of layered BaPd2As2 pnictide superconductor: A first principles investigation
摘要： BaPd2As2, belonging to the 122 pnictide group, is an iron-free layered transition metal arsenide which exhibits superconductivity at low temperature when realized in the ThCr2Si2 type structure (I4/mmm). We have performed density functional theory (DFT) based calculations to investigate the structural, elastic, electronic, thermodynamic, and optical properties of BaPd2As2 in this study. The structural, elastic, and the band structure features are compared with the available experimental and theoretical results. Pressure and temperature dependences of various important thermodynamic functions, e.g., bulk modulus, specific heats at constant pressure and volume, coefficient of volume thermal expansion, and Debye temperature are studied in details for the first time. The optical parameters of BaPd2As2 are also studied in details for the first time. The optical properties compliment the electronic band structure characteristics. Optical constants show significant dependence of the state of polarization of the incident electric field. BaPd2As2 exhibits high reflectance in the infrared and near-visible region and strongly absorbs the ultraviolet radiation. The relevance of the electronic energy density of states and the characteristic phonon frequency to superconductivity in BaPd2As2 is also discussed.
关键词： BaPd2As2 superconductor,Density functional theory,Electronic band structure,Optical properties,Elastic constants,Thermodynamic properties
更新于2025-09-10 09:29:36
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High-Yield Formation of Graphdiyne Macrocycles Through On-Surface Assembling and Coupling Reaction
摘要： Rationally designed halogenated hydrocarbons are widely used building blocks to fabricate covalent-bonded carbon nanostructures on surface through a reaction pathway involving generation and dissociation of organometallic intermediates and irreversible covalent bond formation. Here we provide a comprehensive picture of the on-surface-assisted homocoupling reaction of 1,3-bis(2-bromoethynyl)benzene on Au(111), aiming for the synthesis of graphdiyne nanostructures. Submolecular resolution scanning tunneling microscopy and noncontact atomic force microscopy observations identify the organometallic intermediates and their self-assemblies formed in the dehalogenation process. The demetallization of the organometallic intermediates at elevated temperatures produces butadiyne moieties that spontaneously formed two different covalent structures, i.e. graphdiyne zigzag chains and macrocycles, whose ratio was found to depend on the initial coverage of organometallic intermediates. At the optimal condition, the stepwise demetallization and cyclization led to a high yield production of graphdiyne macrocycles up to 95 %. Statistical analysis and theoretical calculations suggested that the favored formation of macrocycles was resulted from the complex interplay between thermodynamic and kinetic processes involving the organometallic bonded intermediates and the covalently bonded butadiyne moieties.
关键词： on-surface reaction,graphdiyne macrocycle,organometallic intermediate,scanning tunneling microscopy,noncontact atomic force microscopy,thermodynamic and kinetic control
更新于2025-09-10 09:29:36
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Thermodynamic Analysis of the Growth of Silicon Carbide Ingots in a Reducing Atmosphere
摘要： We have analyzed phase equilibria in the Si–C–H–Ar system during silicon carbide ingot growth by the modified Lely method. The results indicate that the addition of even small amounts of hydrogen to an inert carrier gas leads to a sharp increase in the rate of carbon transport through the gas phase, mediated by volatile hydrocarbons, primarily acetylene, and prevents carbon enrichment in the solid source and corrosion of the graphite equipment in the single-crystal seed region.
关键词： silicon carbide,modified Lely method,hydrogen,thermodynamic analysis
更新于2025-09-09 09:28:46