Junjie Miao

Path‐Guided Wrinkling of Nanoscale Metal Films

The experimental part of this work was supported by the funds from NSFC (10974037), NBRPC (2010CB934102), International S&T Cooperation Program (2010DFA51970) and Eu-FP7 (No. 247644). The modeling and simulations were supported by the US National Science Foundation (Grants No. 0926851). We thank Dr. Zhang Jianming for helpful discussions.

MTMO grayscale photomask.

We present a new class of simple, cheap and stable grayscale photomasks based on the metal-transparent-metallic-oxides (MTMO) systems by laser direct writing in metal films. For obtaining high resolution and grainless grayscale patterns we developed a refinement method of the films, in which the nanometer size effect may play a significant role for the improvement. We propose a layered oxidation model and a grain model for the mechanism of In- and Sn-based MTMO systems. The masks have a wide application wavelength range at least from 350 to 700 nm. Three-dimensional microstructures have been successfully fabricated by using the MTMO grayscale masks.

TiO 2 micro-devices fabricated by laser direct writing

Constructing micro/nanostructures based on TiO2 has attracted increasing attention due to the excellent properties of TiO2. In this study, we report a simple method to directly fabricate TiO2 micro-devices, including Fresnel lens, gear structures and suspended beams only by laser direct writing and selective-etching processing. This route shows great potential in fabricating TiO2 structures for micro-electro-mechanical systems, diffractive optical elements and bio-applications, owing to its maskless process, low cost, and flexible dry/wet alternative etching treatment.

Far-Field Focusing of Spiral Plasmonic Lens

In this paper, we study the nanoscale-focusing effect in the far field for a spiral plasmonic lens with a concentric annular groove by using finite-difference time domain simulation. The simulation result demonstrates that a left-hand spiral plasmonic lens can concentrate an incident right-hand circular polarization light into a focal spot at the exit surface. And this spot can be focused into far field due to constructive interference of the scattered light by the annular groove. The focal length and the focal depth can be adjusted by changing the groove radius and number of grooves within a certain range. These properties make it possible to probe the signal of spiral plasmonic lens in far field by using conventional optical devices.

Micro-optical elements fabricated by metal-transparent-metallic-oxides grayscale photomasks

One-step gray-tone lithography is the most effective approach to making three-dimensional (3D) micro-optical elements (MOEs). Metal-transparent-metallic-oxide (MTMO) grayscale masks are novel and quite cost effective. In this paper, through the successful fabrication of 3D SiO(2) MOEs by gray-tone lithography and reactive ion etching, we thoroughly investigate the practical technique needs of MTMO grayscale masks on metallic nanofilms. Design calibration, pattern transfer, resolution, lifetime, and mask protection of grayscale masks have been verified. This work shows that the MTMO grayscale photomask has good practical applicability in the laboratory and in industry.

Bismuth nanowire growth under low deposition rate and its ohmic contact free of interface damage

High quality bismuth (Bi) nanowire and its ohmic contact free of interface damage are quite desired for its research and application. In this paper, we propose one new way to prepare high-quality single crystal Bi nanowires at a low deposition rate, by magnetron sputtering method without the assistance of template or catalyst. The slow deposition growth mechanism of Bi nanowire is successfully explained by an anisotropic corner crossing effect, which is very different from existing explanations. A novel approach free of interface damage to ohmic contact of Bi nanowire is proposed and its good electrical conductivity is confirmed by I-V characteristic measurement. Our method provides a quick and convenient way to produce high-quality Bi nanowires and construct ohmic contact for desirable devices.

Transparency conversion mechanism and laser induced fast response of bimetallic Bi/In thin film

Transparency conversion mechanism and laser induced fast response velocity of bimetallic Bi/In thin film is studied. Heat-treatment and laser exposure with different pulse width induced transparency is investigated by using ultraviolet-visible (UV-VIS) spectrometer, X-ray diffraction (XRD), Auger Electron Scan (AES), microscope and field emission scanning electron microscopy (FESEM). Research results show that oxidation is regarded as the reason for heat treated and long-pulsed laser exposure induced transparency conversion. Laser ablation is demonstrated to be the main reason for short-pulsed (~7ns) laser induced transparency conversion. For Bi/In thin film covered with a protection layer of (ZnS)0.85(SiO2)0.15 thin film, it exhibit fast response as fast as less than 100ns. The conclusions contribute to understanding and development of materials for thermal resist, photomask, optical storage medium and transparent conductive oxide with better performance.