Wafer-scale freestanding vanadium dioxide film.
Ontology highlight
ABSTRACT:
SUBMITTER: Ma H
PROVIDER: S-EPMC8654297 | biostudies-literature | 2021 Dec
REPOSITORIES: biostudies-literature
Publications
Wafer-scale freestanding vanadium dioxide film.
Ma He H Xiao Xiao X Wang Yu Y Sun Yufei Y Wang Bolun B Gao Xinyu X Wang Enze E Jiang Kaili K Liu Kai K Zhang Xinping X
Science advances 20211208 50
Vanadium dioxide (VO<sub>2</sub>), with well-known metal-to-insulator phase transition, has been used to realize intriguing smart functions in photodetectors, modulators, and actuators. Wafer-scale freestanding VO<sub>2</sub> (f-VO<sub>2</sub>) films are desirable for integrating VO<sub>2</sub> with other materials into multifunctional devices. Unfortunately, their preparation has yet to be achieved because the wafer-scale etching needs ultralong time and damages amphoteric VO<sub>2</sub> whethe ...[more]
Similar Datasets
Project description:For applications as high-brightness light-emitting-diodes, a bow-free freestanding gallium nitride (GaN) wafer 2 inch in diameter and ∼185 μm in thickness was fabricated by process-designing pit and mirror GaN layers grown via hydride-vapor-phase epitaxy, laser lift-off, N-face polishing of the pit GaN layer, and three-step polishing of the mirror GaN layer using 3.0 μm-, 0.5 μm-, and 50 nm-diameter diamond abrasives and by inductively-coupled-plasma reactive-ion etching. The considerably large concave shape of the GaN wafer could be decreased by controlling the removal amount of the Ga-face mirror layer during the first step of the polishing process, which approached a bow-free shape or changed with further polishing; this well correlated with the residual stress of the polished GaN wafer.
| S-EPMC9054521 | biostudies-literature
Project description:Efficient thermal management at the nanoscale is important for reducing energy consumption and dissipation in electronic devices, lab-on-a-chip platforms and energy harvest/conversion systems. For many of these applications, it is much desired to have a solid-state structure that reversibly switches thermal conduction with high ON/OFF ratios and at high speed. Here we describe design and implementation of a novel, all-solid-state thermal switching device by nanostructured phase transformation, i.e., modulation of contact pressure and area between two poly-silicon surfaces activated by microstructural change of a vanadium dioxide (VO2) thin film. Our solid-state devices demonstrate large and reversible alteration of cross-plane thermal conductance as a function of temperature, achieving a conductance ratio of at least 2.5. Our new approach using nanostructured phase transformation provides new opportunities for applications that require advanced temperature and heat regulations.
| S-EPMC5540922 | biostudies-literature
Project description:Transfer printing of thin-film nanoelectronics from their fabrication wafer commonly requires chemical etching on the sacrifice of wafer but is also limited by defects with a low yield. Here, we introduce a wafer-recyclable, environment-friendly transfer printing process that enables the wafer-scale separation of high-performance thin-film nanoelectronics from their fabrication wafer in a defect-free manner that enables multiple reuses of the wafer. The interfacial delamination is enabled through a controllable cracking phenomenon in a water environment at room temperature. The physically liberated thin-film nanoelectronics can be then pasted onto arbitrary places of interest, thereby endowing the particular surface with desirable add-on electronic features. Systematic experimental, theoretical, and computational studies reveal the underlying mechanics mechanism and guide manufacturability for the transfer printing process in terms of scalability, controllability, and reproducibility.
| S-EPMC6077709 | biostudies-literature
Project description:Vanadium dioxide (VO2) has garnered significant attention as a material for actively tunable infrared (IR) modulators due to its reversible and responsive modulation effect on IR radiation, which is accompanied by its intrinsic insulator-metal phase transition (IMT). Here, we propose a multilayer device structure that integrates VO2 film with microheater and interdigitated electrodes for cooperative thermal-electric field control of IMT. Our results demonstrate that while intense electric fields can trigger abrupt IMT, deep modulation of IR radiation requires energy integration through Joule heating, which limits the response time of IR transmission controlled by electric field. Thus, cooperative thermal-electric field control, which provides a constant, uniform temperature field while electrically switching the IMT, is more effective for achieving a faster response time and retaining the intrinsic modulation depth of VO2-based IR modulators. Our findings offer valuable insights for the development of VO2-based IR modulators with improved performance.
| S-EPMC10720291 | biostudies-literature
Project description:Vanadium dioxide (VO2) thin films of different thicknesses were prepared by regulating the deposition time (2, 2.5, 3, and 3.5 h). The impact of deposition time on the microstructure, surface morphology, and cross-section morphology was investigated. The results showed that the grain size increased with the film thickness. Meanwhile, the influence of film thickness on the residual stress was evaluated by X-ray diffraction. The phenomenon of "compressive-to-tensile stress transition" was illustrated as the thickness increased. The change of dominant mechanism for residual stress was used for explaining this situation. First, the composition of residual stress indicates that growth stress play a key role. Then, the effect of "atomic shot peening" can be used to explain the compressive stress. Lastly, the increased grain size, lower grain boundary density, and "tight effect" in the progress of film growth cause tensile stress.
| S-EPMC10386697 | biostudies-literature
Project description:A wafer scale bulge testing system has been constructed to study the mechanical properties of thin films and microstructures. The custom built test stage was coupled with a pressure regulation system and optical profilometer which gives high accuracy three-dimensional topographic images collected on the time scale of seconds. Membrane deflection measurements can be made on the wafer scale (50-150 mm) with up to nanometer-scale vertical resolution. Gauge pressures up to 689 kPa (100 psi) are controlled using an electronic regulator with and accuracy of approximately 0.344 kPa (0.05 psi). Initial testing was performed on square diaphragms 350, 550, and 1200 microm in width comprised of 720+/-10 nm thick low pressure chemical vapor deposited silicon nitride with approximately 20 nm of e-beam evaporated aluminum. These initial experiments were focused on measuring the system limitations and used to determine what range of deflections and pressures can be accurately measured and controlled. Gauge pressures from 0 to approximately 8.3 kPa (1.2 psi) were initially applied to the bottom side of the diaphragms and their deflection was subsequently measured. The overall pressure resolution of the system is good (approximately 350 Pa) but small fluctuations existed at pressures below 5 kPa leading to a larger standard deviation between deflection measurements. Analytical calculations and computed finite element analysis deflections closely matched those empirically measured. Using an analytical solution that relates pressure deflection data for the square diaphragms the Young's modulus was estimated for the films assuming a Poisson's ratio of v=0.25. Calculations to determine Young's modulus for the smaller diaphragms proved difficult because the pressure deflection relationship remained in the linear regime over the tested pressure range. Hence, the calculations result in large error when used to estimate the Young's modulus for the smaller membranes. The deflection measurements of three 1200 x 1200 microm(2) Si(3)N(4-x) membranes were taken at increased pressures (>25 kPa) to increase nonlinearity and better determine Young's modulus. This pressure-deflection data were fit to an analytical solution and Young's modulus estimated to be 257+/-3 GPa, close to those previously reported in literature.
| S-EPMC2892528 | biostudies-other
Project description:Au-Au surface activated bonding (SAB) using ultrathin Au films is effective for room-temperature pressureless wafer bonding. This paper reports the effect of the film thickness (15-500 nm) and surface roughness (0.3-1.6 nm) on room-temperature pressureless wafer bonding and sealing. The root-mean-square surface roughness and grain size of sputtered Au thin films on Si and glass wafers increased with the film thickness. The bonded area was more than 85% of the total wafer area when the film thickness was 100 nm or less and decreased as the thickness increased. Room-temperature wafer-scale vacuum sealing was achieved when Au thin films with a thickness of 50 nm or less were used. These results suggest that Au-Au SAB using ultrathin Au films is useful in achieving room-temperature wafer-level hermetic and vacuum packaging of microelectromechanical systems and optoelectronic devices.
| S-EPMC7281518 | biostudies-literature
Project description:Remarkable improvements in both structural and optical properties of wafer-scale hexagonal boron nitride (h-BN) films grown by metal-organic chemical vapor deposition (MOCVD) enabled by high-temperature post-growth annealing is presented. The enhanced crystallinity and homogeneity of the MOCVD-grown h-BN films grown at 1050 °C is attributed to the solid-state atomic rearrangement during the thermal annealing at 1600 °C. In addition, the appearance of the photoluminescence by excitonic transitions as well as enlarged optical band gap were observed for the post-annealed h-BN films as direct consequences of the microstructural improvement. The post-growth annealing is a very promising strategy to overcome limited crystallinity of h-BN films grown by typical MOCVD systems while maintaining their advantage of multiple wafer scalability for practical applications towards two-dimensional electronics and optoelectronics.
| S-EPMC6646322 | biostudies-literature
Project description:Graphene films, fabricated by chemical vapor deposition (CVD) method, have exhibited superiorities in high crystallinity, thickness controllability, and large-scale uniformity. However, most synthesized graphene films are substrate-dependent, and usually fragile for practical application. Herein, a freestanding graphene film is prepared based on the CVD route. By using the etchable fabric substrate, a large-scale papyraceous freestanding graphene fabric film (FS-GFF) is obtained. The electrical conductivity of FS-GFF can be modulated from 50 to 2800 Ω sq-1 by tailoring the graphene layer thickness. Moreover, the FS-GFF can be further attached to various shaped objects by a simple rewetting manipulation with negligible changes of electric conductivity. Based on the advanced fabric structure, excellent electrical property, and high infrared emissivity, the FS-GFF is thus assembled into a flexible device with tunable infrared emissivity, which can achieve the adaptive camouflage ability in complicated backgrounds. This work provides an infusive insight into the fabrication of large-scale freestanding graphene fabric films, while promoting the exploration on the flexible infrared camouflage textiles.
| S-EPMC8844486 | biostudies-literature
Project description:Radiative cooling in smart windows using VO2 - a dynamic thermal management material, is of potential interest for enhancing energy savings in buildings due to its both solar and emittance tuneability in response to changing temperatures. However, studies related to the effects of VO2 thin film microstructure in a multilayer system on emissivity regulation are currently lacking. The present study addresses the thermochromic and emissivity performance of VO2/ZnSe/ITO/Glass Fabry-Perot (F-P) cavity thin film system, by manipulating the porosity in VO2 thin film. The device is fabricated by commercially feasible physical vapor deposition methods such as sputtering and thermal evaporation, most suitable for mass production. The optimized sample with porous VO2 delivers an enhanced long-wave infrared (LWIR) emissivity contrast of Δɛ LWIR ≥ 0.4 preserving a high visible transparency T lum(avg) of ∼41 % compared to dense VO2. Then finite difference time domain (FDTD) simulation is performed to further understand the effects of varying VO2 porosity and ZnSe thickness on the F-P cavity properties. The reduced low-temperature ɛ LWIR (0.1-0.2) gives this film better energy saving in regions where warming demand is dominant as simulated by EnergyPlus.
| S-EPMC11501869 | biostudies-literature