Xinghui Wu

Memristor‐Integrated Voltage‐Stabilizing Supercapacitor System

Voltage-stabilized supercapacitors: A single supercapacitor formed with PCBM/Pt/IPS nanorod-array electrodes is designed and delivers enhanced areal capacitance, capacitance retention, and excellent electrical stability under bending, while a significant voltage-decrease is observed during the discharging process. Once integrated with the memristor, the memristor-integrated supercapacitor systems deliver an extremely low voltage-drop, indicating greatly enhanced voltage-stabilizing features.

Porous Light-Emitting Diodes With Patterned Sapphire Substrates Realized by High-Voltage Self-Growth and Soft UV Nanoimprint Processes

Nanostructured GaN-based light-emitting diode (LED), with its high performance on light extraction efficiency, has attracted significant attention for the potential application in solid state lighting. However, patterning structures at nanoscale feature size with large area and low cost is of great importance and hardness. In this paper, a 2 inch anodic aluminum oxide (AAO) template was used as the initial mold to copy the photonic-crystal-like structures (PCLSs) on a blue-light LED by soft UV nanoimprint lithography. An additional solute, aluminum oxalate hydrate, is employed to overcome the burn-through issue in the high-voltage anodization which is critical for the fabrication of the large-pore (250-500 nm) AAO. The photoluminescence and electroluminescence enhancements of the patterned LED device with 150-nm-deep PCLSs are, respectively, 45% and 11.4% compared with the un-patterned LED device. A 3-D finite-difference time-domain simulation confirms that the light extraction efficiency is enhanced when PCLSs are formed. The proposed method is simple, cheap, repeatable in large area and compatible with the high volume production lines.

Resistive switching behavior of photochemical activation solution-processed thin films at low temperatures for flexible memristor applications

This study explores deep ultraviolet photochemically activated solution-processed metal-oxide thin films at room temperature for fabrication of flexible memristor active resistive layers. An annealing treatment was not required during the process. Solution processed undoped and Mn-doped ZnO thin films served as active layers in the resistive random access memory structure, prepared at 145 °C. The carrier transports in high and low electrical fields were dominated by Frenkel–Poole emission and thermionic emission, respectively. The trap energy level, which originated primarily from Vo or the singly charged oxygen vacancy, was calculated at 0.49 eV. A flexible structure consisting of Ag/DUV-ZnO/indium tin oxide/polyethylene terephthalate was fabricated successfully and its mechanical performance was investigated.

Polymer nanopillar array with Au nanoparticle inlays as a flexible and transparent SERS substrate

We report a facile and efficient way to fabricate a highly flexible, transparent and efficient surface-enhanced Raman scattering (SERS) substrate, in which Au nanoparticles (NPs) were embedded into the polymeric nanopillars via a nanoimprint lithography (NIL) method and using an anodic aluminum oxide (AAO) template. The obtained substrate exhibits prominent reproducibility and high sensitivity to Rhodamine 6G (R6G). Moreover, it possesses excellent transparency and flexibility. The SERS intensity acquired from these substrates almost remains constant after 200 bending cycles. Compared with traditional SERS substrates, this substrate represents a novel format with unique advantages, such as being highly flexible, transparent, lightweight, portable and easy to handle. More importantly, it can be scaled up for high-throughput production with low cost.

Fabrication of the porous silicon though a self-assembled porous alumina template

We present the fabrication of porous silicon through a self-assembled porous alumina template(PAT) directly grown on the Si substrate. SEM and UV-vis spectrometer were used to characterize the morphology, size distribution and the reflectivity performance.

Tuning the Wavelength Drift of PZT/PAT Composite Structure

The reflection and absorption performance of orderly porous Pb(Zr0.52Ti0.48)O3 (PZT) on porous alumina template (PAT) structure are investigated, PZT ferroelectric film were deposited on PAT substrate by RF magnetron sputtering process. By controlling the specifications of PZT/PAT nanopores, we could implement the amplitude modulation of absorption edge and reflection. With the decrease of the nanopore size, absorption edge are red shift and the amplitude of the reflection are lower. The wavelength drift between the reflection and absorption has been optimized by changing the thickness of PZT film and structure. This provides an excellent reference to the device of absorption edge/stripe requiring careful tuning.

Electronic structure and optical properties of ZnSe from first-principles calculations

We have performed the first-principles calculations in the framework of density functional theory to determine the electronic structure and optical properties of zinc-blende ZnSe.

First-principles study of optical absorption properties of perovskite PbZrxTi1-xO3

The energetic stability, the structural and the electronic properties of perovskite PbZrxTi1-xO3 are systematically investigated by the first-principles. when the x=0.5, the light absorption properties of PZT in non Zirconium-Rich area is the hightest.

Resistive Switching Behaviors In ZnO Thin Films Prepared By Photochemical Activation At Room Temperature

ZnO thin films based resistive switching layer in the Ag/ZnO/ITO structure was fabricated by photochemical activation at low temperature through sol-gel process. The resistive switching characteristics of as fabricated Ag/ZnO/ITO structure are studied.

Uniform and Duty Cycle Tunable Photonic Crystal LEDs Fabricated by Intermediate Mask Layer: Soft UV Nanoimprint Lithography

As an improvement of the conventional nanoimprint lithography, an intermediate mask layer process is invited for photonic crystal pattern transfer on LEDs. Benefit from the smooth effect of the under-layer resist, uniform photonic crystal structure is successfully transferred to the p-GaN surface. The intermediate SiO2 layer has a high etching selectivity to the under-layer resist, which can be used to fabricate nanostructures with tunable duty cycle via one single initial mold. The photonic crystal LED fabricated by the process of intermediate mask layer nanoimprint lithography shows a 3.31 fold PL enhancement to that of the un-patterned LED.