Guo-Bin Ma

Confinement-induced ordering in dewetting and phase separation of polymer blend films.

Dewetting and phase separation of a thin polymer fi lm over a homogeneous surface has been extensively investigated in recent decades. Research was driven either by scientifi c curiosity for general principles of rupture mechanisms [ 1–3 ] or by technical anticipation in fi nding out the conditions for stable lithographic resist layers. [ 4 , 5 ] Depending on the interfacial interactions, there are two possible rupture mechanisms of a polymer fi lm: one occurs via nucleation of dry spots [ 6–8 ] and the other is by spontaneous amplifying the capillary waves caused by thermal fl uctuation. [ 9–11 ] To demonstrate the effect of intermolecular interactions in the process, the infl uence of pattern scale and frequency on morphological evolution of the dewetting pattern of the thin polymer fi lm can be tuned by topographically smooth, yet chemically inhomogeneous self-assembled monolayers. [ 12–15 ] In addition, physical modulations, such as periodic arrays of micro pillars, [ 16 ] stripes, [ 17 , 18 ]

Exchange of electric and magnetic resonances in multilayered metal/dielectric nanoplates

In this work, we have experimentally demonstrated that in a rectangular multilayered Ag/SiO₂ nanoplate array, electric and magnetic resonances are exchanged at the same frequency simply by changing the polarization of incident light for 90°. Both electric and magnetic resonances originate from localized surface plasmons, and lead to negative permittivity and permeability, respectively. The numerical calculations on electromagnetic fields agree with the experiments. The investigations provide a simple building block for a metamaterial to switch electric and magnetic resonances by external excitation field.

Formation of Regular Magnetic Domains on Spontaneously Nanostructured Cobalt Filaments

[*] Prof. M. Wang, Dr. X. P. Huang, Dr. Z. L. Shi, Dr. G. B. Ma, Prof. D. Wu, Prof. R. W. Peng, Prof. N. B. Ming National Laboratory of Solid State Microstructures, Nanjing University Nanjing 210093 (P.R. China) E-mail: muwang@nju.edu.cn Dr. M. Konoto Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Higashi 1-1-1, Tsukuba, 305-8562 (Japan)

Metallic stereostructured layer: An approach for broadband polarization state manipulation

In this letter, we report a full-metallic broadband wave plate assembled by standing metallic L-shaped stereostructures (LSSs). We show that with an array of LSSs, high polarization conversion ratio is achieved within a broad frequency band. Moreover, by rotating the orientation of the array of LSSs, the electric components of the reflection beam in two orthogonal directions and their phase difference can be independently tuned. In this way, all the polarization states on the Poincare sphere can be realized. As examples, the functionalities of a quarter wave plate and a half wave plate are experimentally demonstrated with both reflection spectra and focal-plane-array imaging. Our designing provides a unique approach in realizing the broadband wave plate to manipulate the polarization state of light.

Electrodeposition of single-crystalline silver pearl chains

We report in this letter the fabrication of unique single-crystalline silver filaments with periodic, pearl-chain-like structures by electrodeposition without using any templates, surfactants, and additives. Fourier transform infrared spectroscopy, infrared focus-plane-array imaging, and numerical simulations demonstrate that the excited surface waves may sustain on the silver “pearl chains” in midinfrared range. Based on the propagation features of surface waves on the silver filaments, we suggest that such a structure can be applied for light transmission in midinfrared range.

Ge-dot/Si multilayered structures through Ni-induced lateral crystallization

We demonstrate a method for fabricating high-quality Ge-dot/Si multilayered structures. High-density self-assembled Ge dots are grown on amorphous Si layer periodically by low-pressure chemical vapor deposition, and then the amorphous Si are crystallized through Ni-based metal-induced lateral crystallization. Optical microscopy, micro-Raman spectroscopy, and electron microscopy observations reveal that the crystallized Si film has large leaflike grains elongated along the lateral crystallization direction, which shows (110) preference. Furthermore, this preference is found to deliver to different Si layers. The strain shift of Ge dots deduced from Raman spectroscopy reveals a formation of a high-quality interface between the crystallized Si and Ge dot.

Synthesis of a Novel Nanostructure of Rutile Titania by Sonochemical Method

Chestnut-bur-like rutile titania assemblies are successfully synthesized by a sonochemical method. Scanning electron microscopy and transmission electron microscopy analyses reveal that the assemblies are formed by radial coagulation of rutile acicular nanocrystals. Effects of experimental conditions on the phase and structure of the products are also presented.

Fabrication of Ge-dots/Si Multilayered Structures by Combination of Low-Pressure CVD and Ni-Induced Lateral Crystallization

Self-assembled Ge quantum dots have attracted a great deal of interests for the realization of silicon- based quantum electronic and optoelectronic devices, such as mid-infrared quantum dot photodetectors, laser, resonant tunnelling diodes, etc. Here, we report on the fabrication of the high density Ge-dots/Si multilayered structure films combining LPCVD and Ni-based MILC processing. The present work is a promising fabrication method to obtain high quality Ge-dots/Si multilayered structure films

3-D Self-Assembled ZnSnO3 Nanoparticles: One-Step Solid-State Synthesis

By means of solid-state reactions method, ZnSnO3 nanoparticles were prepared in the reactions of ZnCl2 and SnCl4·5H2O with KOH in the presence of added KCl crystal, and were assembled into 3-D aggregates with tetragonal-like shape in the size range of 20-200 nm. The products were characterized by powder X-ray diffraction (XRD), and the microstructures of the samples were investigated by transmission electron microscope (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscope (HRTEM) in detail. Probable mechanisms for the formation of such tetragonal-like shape of ZnSnO3 3-D aggregates are proposed.