In this talk I will present our recent research on the design and preparation of three-dimensional (3D) hierarchical metamaterials and two-dimensional (2D) hierarchical metasurfaces as novel SERS substrates with ultrahigh sensitivity and reproducibility. The former substrate consists of close-packed arrays of nanoholes and uniformly distributed mesopores over the bulk and the second comprised of sub-wavelength-sized conical nanopores and sub-5-nm nanogrooves. Both substrates employ a cascaded field enhancement mechanism, leading to the ultrahigh sensitivity, and have a (quasi)periodic arrangement of plasmonic near-field hot-spots, ensuring excellent structural and signal reproducibility. In particular, the latter substrate is highly mechanically flexible, allowing for extreme adaptability to complex working conditions such as build-in real-time monitoring of trace level molecules.
 X. Zhang, Y. Zheng, X. Liu, W. Lu, J. Dai, D. Y. Lei* & D. R. MacFarlane*, “Hierarchical porous plasmonic metamaterials for reproducible ultrasensitive surface-enhanced Raman Spectroscopy”, Advanced Materials 27, 1090-1096 (2015).
 C. Xu, Y. Zhou, S. Lyu, Y.-L. Zhang, H. Yao, D. Mo, J. L. Duan* & D. Y. Lei*, “Highly flexible, hierarchical porous plasmonic metasurfaces for reproducible, ultrasensitive surface-enhanced Raman spectroscopy”, under preparation (2017).
 K. Chen, X. Zhang, Y.-L. Zhang, D. Y. Lei, H. Li, T. Williams & D. R. MacFarlane, "Highly ordered Ag/Cu hybrid nanostructure arrays for ultrasensitive surface-enhanced Raman spectroscopy", Advanced Materials Interfaces 3, 1600115 (2016).
A new trial of standing wave type bi-directional moving linear ultrasonic motor has been studied in this paper. Finite
element modeling analysis revealed that by connecting three rectangular metal plates in different lengths together by two
weak links, two bending vibration mode standing waves, i.e., one in sine wave and the other one in cosine wave, with
nearly the same wavelength can be formed in the middle plate. With four pieces of PZT-4 piezoceramics mounted to the
middle plates as driving elements, a new type of bi-directional linear moving ultrasonic motor of 60mm in length and
10mm in width has been designed, fabricated and characterized. The following performances have been achieved:
maximum velocity 220mm/s, maximum output force 180gf, and resolution better than 0.2μm.
Ultrasonic motor (USM) as a new type of driving motor has many good features compared with conventional
electromagnetic motor. However, due the content of Pb in the driving element piezoelectric ceramics, Pb(Zr<sub>x</sub>,Ti<sub>1-x</sub>)O<sub>3</sub>
(PZT), the application of USM will be restricted from the viewpoint of environmental requirement. In this paper lead
free piezoceramics, Mn doped 0.94(Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub> -0.06BaTiO<sub>3</sub>(BNT-BT), was used as driving element in ultrasonic
motor in replacing PZT. Though the piezoelectric property of BNT-BT ceramic is inferior to that of PZT, the USM with
BNT-BT driving element shows promising result and potential to replace PZT ceramic in application of ultrasonic
Although metal/semiconductor and oxide/semiconductor junctions have long been studied in the areas of microelectronics, new phenomena and interests arise from time to time. In particular, in the realm of nanotechnology where materials are shrunk at a length scale of nanometers, the role of heterojunctions in controlling the overall characteristics of the system will become more and more important. In this paper, we will show our recent results on the light emission and charge transport properties of metal/ZnO and oxide/ZnO system at different dimensionalities. On one hand, it is found that by capping metal on ZnO, it is possible to excite the surface plasmon polaritorn at the metal/ZnO interface and resonantly couple it with the spontaneous recombination of ZnO. This results in a significant enhancement of emission efficiency of ZnO. On the other hand, providing an oxidic overlayer (AlOx) is present on ZnO, a focused electron beam can be used to locally modify optical and electrical properties of ZnO. Under electron bombardment, we find the emission profile of ZnO gradually changes from green-yellow emitting into ultra-violet emitting while the conductivity decreases by more than two orders of magnitude at the same time. Well-defined sub-micron patterns with tunable optical and electrical properties can be fabricated on 2-D ZnO films and 1-D nanoribbons by carefully controlling the dose and energy density of the electron beam. Since ZnO is a versatile material, we believe our studies will shed light on the further use of ZnO in frontier technologies such as gas sensing, display technology, catalysis, spintronics, etc.
Recently, many efforts have been made to improve the device performance of nanocrystal memory by replacing the SiO<sub>2</sub> with various high dielectric constant (high-<i>k</i>) materials, especially embedded with Ge nanocrystals. This paper demonstrates the floating gate memory effect by embedding nanometer-sized Ge nanocrystals in hafnium aluminate (HfAlO) high-<i>k</i> gate dielectric. A 5 nm-thick amorphous thin film of HfAlO was first deposited on (100) p-Si substrates as a tunneling gate oxide layer by laser molecular beam epitaxy deposition using a HfO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> composite target. Well-defined (~10 nm in diameter) nanometer-sized Ge dots were subsequently deposited on this thin tunneling gate oxide followed by a 30 nm-thick top control gate oxide of HfAlO. Transmission electron microscopy has been carried out for a detailed study of structural properties of the Ge nanocrystals embedded in the HfAlO films, and their relationships to electrical properties. Electrical properties have been characterized by means of high-frequency capacitance-voltage (C-V) and current-voltage (I-V) measurements on the metal-oxide-semiconductor capacitors. A counter-clockwise hysteresis C-V loop has been obtained and a threshold voltage shift of 1.0 V has been achieved indicating stored electrons (up to a density of 2x10<sup>12</sup> cm<sup>-2</sup>) in the Ge-nanodots floating gate and thus the memory effect. Time-dependent I-V measurement also showed low leakage current of floating gate system. These results suggest that the Ge nanocrystals embedded in HfAlO are promising for floating gate memory device application.