Papers by Author: Li Shi Wen

Abstract: The high quality ZAO thin films were produced by DC reaction magnetron sputtering technology. The XRD, electrical and optical properties of ZAO thin films were particularly investigated. The results show that ZAO films are polycrystalline hexagonal wurtzite structure，and Al₂O₃ crystal phase are not found. At the same time，the high quality ZAO films with the minimum resistivity of 4.5x×10^-4Ω·㎝, the transmittance in visible region above 80% and the reflectivity in IR region above 70% are gained.

Abstract: P-type microcrystalline silicon films prepared by electron cyclotron resonance（ECR）PECVD are studied here. Silane diluted with Ar (SiH4/Ar=1/19) is used as a source gas and diborane (B2H6) diluted with H2 (100ppm) as doping gases. The effect of flow rate of doping gas on the microstructures and electrical properties of the films were investigated. Raman spectroscopy and X-ray diffraction were used to determine the film structure; AFM was employed to characterize the film surface topography; Hall measurements were carried out on the doped films to determine the carrier type, carrier concentration, and Hall mobility. The optical quality was measure by transmission spectrum.

Abstract: F-doped TiO2 has exhibited superior photocatalytic activity. However, its electronic structures and photocatalysis mechanism are still unclear. In the present work, the structural optimization and electronic structure of F-doped anatase TiO2 have been investigated by means of the first-principles pseudopotential total energy method. It has been demonstrated that F doping would modify the valence band at the lower energy direction in the F-doped TiO2. Calculation results confirm that doping of fluorine would not shift the absorption edge into the visible light region. Instead, we attributed its photocatalytic activity to the enhancement of the oxidative power of F-doped TiO2.

Abstract: Silicone rubber (SIR) samples are exposed to CF4 capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) at radio frequency (RF) power of 60–200 W for a treatment time up to 20 min, respectively. Static contact angle is employed to estimate the change of hydrophobicity of the silicone rubber modified by the two coupled types of CF4 RF plasma. A milder enlargement of static contact angle of SIR samples modified by ICP treatment is observed compared with that by CCP treatment. The hydrophobicity of the modified SIR surface by CCP treatment increases to a maximum, and further decreases toward the hydropholicity. The higher self-bias on the SIR samples being modified by CCP treatment than that by ICP treatment leads to the more dramatic physical and/or chemical reaction on the SIR surface, resulting in the competition between fluorination and ablation or etching.

Abstract: TiO2 films were deposited by using mid-frequency twin magnetron reactive sputtering technique at ambient temperature on quartz and Si wafer. The films were annealed after deposition. The phase composition and surface morphology of the TiO2 films were characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy, while the optical properties and contact angle were measured using a UV-Vis spectrophotometer and a contact angle meter. It is indicated that anatase phase dominates below 900°C and a mixture of rutile and anatase exists in the film annealed at 1000°C. Furthermore, the hydrophilic property depends on phase composition and morphological change in TiO2 films.