Effect of memory electrical switching in metal/vanadium oxide/silicon structures with VO2 films obtained by the sol-gel method

Seed Layer Engineering for Crack-free Sol-gel Alumina Deposition on GFETs

Low cost and low thermal budget based spin-coated sol-gel Alumina was explored as a dielectric/passivation layer for GFET. Post thermal annealing, the crack was observed in sol-gel Alumina layer exactly above the graphene channel. The possible mechanism of crack could be graphene lateral restoring movement due to (i) Thermal Expansion Coefficient (TEC) difference between graphene and adjacent layers and (ii) shrinkage stress generated during the solvent removal process. Based on the crack formation phenomenon, a combination of different annealing schemes (low thermal budget DUV annealing) and …

Investigations on the improved cycling stability of Kazakhstanite phase Fe-V-O layered oxide by using superconcentrated electrolytes: Generalized solubility limit approach (Part I)

In this article, we address the issue of vanadium dissolution pertinent in the layered Fe5V15O39(OH)9.9H2O using the solubility limit approach. This layered oxide is prepared via a low-cost solution phase synthesis route and crystallizes in the Kazakhstanite phase (Space Group: C2/m), confirmed using selected area electron diffraction and x-ray diffraction.The layered oxide exhibits the 2 electron redox reaction of vanadium (V5+ to V3+) along with the 1 electron redox reaction of iron within the voltage window of 1.5-3.8V. This results in a high specific capacity of ~350mAhg-1 which can be ext…

Evidence for mechanical softening-hardening dual anomaly in transition metals from shock compressed vanadium

Solid usually becomes harder and tougher under compression, and turns softer at elevated temperature. Recently, compression-induced softening and heating-induced hardening (CISHIH) dual anomaly was predicted in group VB elements such as vanadium. Here, the evidence for this counterintuitive phenomenon is reported. By using accurate high-temperature high-pressure sound velocities measured at Hugoniot states generated by shock-waves, together with first-principles calculations, we observe not only the prominent compression-induced sound velocity reduction, but also strong heating-induced sound v…

Experimental Demonstration of Dynamic Thermal Regulation using Vanadium Dioxide Thin Films

We present an experimental demonstration of passive, dynamic thermal regulation in a solid-state system with temperature-dependent thermal emissivity switching. We achieve this effect using a multilayered device, comprised of a vanadium dioxide (VO2) thin film on a silicon substrate with a gold back reflector. We experimentally characterize the optical properties of the VO2 film and use the results to optimize device design. Using a calibrated, transient calorimetry experiment we directly measure the temperature fluctuations arising from a time-varying heat load. Under laboratory conditions, w…

使用二氧化钒的超高耐久度硅光子存储器

Ultra-high endurance silicon photonic memory using vanadium dioxide

针对光子存储器因指标权衡难以实现超高耐久度的问题，提出使用二氧化钒的硅光子存储器，实现高达10^7次循环无退化且占位面积低于5 μm，可应用于原位训练的光子神经网络。

An Optimized Self-Adaptive Thermal Radiation Turn-Down Coating with Vanadium Dioxide Nanowire Array

High performance metasurfaces for thermal radiative cooling applications can be identified using computational optimization methods. This work has identified an easy-to-fabricate temperature phase transition VO2 nanowire array laid atop dielectric BaF2 Fabry-Perot cavity-on-metal with total coating thickness of 2 um. This optimized structure has ability to self-adaptively switch between high reflectance at low temperature to high emissivity at high temperature in the broad thermal infrared spectrum. This design demonstrates exceptional turn-down figure-of-merit compared to previously realized …

Ultrafast reprogrammable multifunctional vanadium-dioxide-assisted metasurface for dynamic THz wavefront engineering

In this paper, for the first time, a new generation of ultrafast reprogrammable multi-mission bias encoded metasurface is proposed for dynamic THz wavefront engineering by employing VO2 reversible and fast monoclinic to tetragonal phase transition. The multi-functionality of our designed VO2 based coding metasurface (VBCM) was guaranteed by elaborately designed meta-atom comprising three-patterned VO2 thin films whose operational statuses can be dynamically tuned among four states of "00"- "11" by merely changing the biasing voltage controlled by an external FPGA platform. Capitalizing on such…

Process Yield and Device Stability Improvement for Sol-gel Alumina Passivation layer based GFETs

The stability of GFET devices is a major problem and needs a good passivation layer for the same. Low cost and low-temperature sol-gel alumina passivation layer-based GFETs is studied here with the goals to improve stability of the device and achieve high process yield. The process yield and device stability are explored for two different molarities of 0.1 M and 0.05 M. The parameters like mobility, trap charge density, minimum conductivity plateau width and minimum conductivity are extracted to compare the stability of devices. The results indicate that GFETs with 0.1 M have problems of proce…

基于铝基非对称法布里-珀罗谐振结构上超薄氧化钒的动态多色切换

Dynamic Multi Color Switching using Ultrathin Vanadium Oxide on Aluminium based Asymmetric Fabry-Perot Resonant Structure

本工作提出一种基于铝基非对称法布里-珀罗谐振结构的超薄VO₂薄膜，通过低热预算大气氧化法合成，利用其相变特性实现了覆盖大色域的动态多色切换，在显示、热致变色及可见光伪装领域具应用潜力。

多孔介质中蒸发诱导的溶胶-凝胶转变

Sol-gel transition by evaporation in porous media

本文通过NMR和X射线显微断层成像技术，研究了多孔介质中溶胶-凝胶转变过程的干燥动力学，揭示了蒸发前沿推进机制及不同干燥阶段对最终凝胶分布均匀性的影响，为多孔文物加固和土木工程提供理论依据。