Chaobo Li

Femtosecond direct laser writing of gold nanostructures by ionic liquid assisted multiphoton photoreduction

Amino-terminated ionic liquid assisted multiphoton photoreduction (IL-MPR) was developed for the direct writing of subwavelength gold nanostructures in AuCl4- ions aqueous solution by femtosecond laser. It was revealed that the carbon chain length was crucial for morphology and size control of gold nanostructures. A 228 nm width of gold nanostructure, which was beyond the optical diffraction limit, was fabricated by the matching between IL and the power and scanning speed of the laser beam. The measured conductivity is of the same order as that of bulk gold. Furthermore, we successfully fabricated a U-shaped terahertz planar metamaterial whose spectral response is consistent with the theoretical expectation. The IL-MPR nanofabrication protocol is expected to play an important role in the fabrication of fine metallic micro/nanostructures for applications in microelectromechanical systems, nanoelectronics and nanophotonics.

High-precision thickness regulation of graphene layers with low energy helium plasma implantation

In this paper we present a novel method of regulation to obtain graphene layers with homogeneous thickness by means of helium plasma implantation. The obtained graphene layers show neither large deep pits nor loss of lateral dimension. The etching rate can be precisely controlled (one to six atomic layers min(-1) or higher) and it remains consistent regardless of the thickness of the multilayer graphene. This approach is compatible with traditional complementary metal-oxide-semiconductor fabrication technologies and has great potential to modulate the performance of graphene for device applications.

Silicon Nitride Film by Inline PECVD for Black Silicon Solar Cells

The passivation process is of significant importance to produce high-efficiency black silicon solar cell due to its unique microstructure. The black silicon has been produced by plasma immersion ion implantation (PIII) process. And the Silicon nitride films were deposited by inline plasma-enhanced chemical vapor deposition (PECVD) to be used as the passivation layer for black silicon solar cell. The microstructure and physical properties of silicon nitride films were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), spectroscopic ellipsometry, and the microwave photoconductance decay (μ-PCD) method. With optimizing the PECVD parameters, the conversion efficiency of black silicon solar cell can reach as high as 16.25%.

Dehydroxylation action on surface of TiO2 films restrained by nitrogen carrier gas during atomic layer deposition process

A strong influence of nitrogen gas on the content of surface hydroxyl groups of TiO2 films by atomic layer deposition (ALD) was investigated by X-ray photoelectron spectroscopy (XPS), contact angle measuring system, and UV–Vis spectrophotometer. XPS spectra of O 1s indicate that the content of surface hydroxyl groups is varied when using N2 as carrier gas. The results of water contact angles and optical reflection spectra show that the content variation of surface hydroxyl groups influences the wetting properties and optical reflectivity of TiO2 films. A surface reaction model is suggested to explain the ALD reaction process using N2 as carrier gas.