Search

Transparent conductive Al-doped zinc oxide thin films for film solar cells were prepared on Si and quartz substrates by radio frequency magnetron sputtering at room temperature. Then, these films were treated by high-density H2/Ar plasma, which was capacitively coupled plasma combined with inductively coupled plasma modes. The density of hydrogen atoms was characterized by optical emission spectroscopy equipped in the system. The structural, electrical, and optical properties of the films were investigated in terms of spectrophotometry, Hall effect measurements, X-ray diffraction, scanning electron microscope, and atomic force microscopy. The effects of low-frequency power on the optical, electrical, and structural properties were discussed. [ABSTRACT FROM PUBLISHER]

Two-dimensional Multiwalled Carbon Nanotube arrays (MWCNTs) were prepared by a novel high-density helicon wave plasma chemical vapor deposition (HWP-CVD) at room temperature. Preliminary studies show that the MWCNTs prepared by this method has strong orientation and is perpendicular to the substrate surface, and exhibit a highly ordered array distribution. The addition of hydrogen can effectively improve the growth rate of MWCNTs and increase the aspect ratio. The height and aspect ratio of MWCNTs can be effectively increased with the increase of growth time. Electrochemical investigation indicated that MWCNTs have high specific capacitance (1.96 mF/cm−2) and excellent rate capability (81.6%). Unlabelled Image • Study on MWCNTs prepared by a novel high-density HWP-CVD for the first time. • Specific capacitance performance and deposition rate of MWCNTs prepared by hydrogen modulated Ar/CH 4 HWP-CVD are improved by 11.8 and 1.7 times, respectively. • The growth model of the preparation of MWCNTs for HWP-CVD is proposed. • MWCNTs have excellent electrochemical performance, which is a potential for energy conversion and energy storage. [ABSTRACT FROM AUTHOR]

We investigated the growth process of vertically-oriented graphene nanosheets (VGs) on a Si substrate by helicon wave plasma chemical vapor deposition (HWP-CVD). The results show that VGs has good vertical orientation on Si and the growth process does not require the catalyst. Modulation of height, thickness and mesh size of vertical graphene nanosheets can be achieved by changing the growth time. It is found that the height of VGs is linear with time. Extremely high growth rate, approximately 0.26 μm/min, is achieved, in contrast to previous studies. The results of Cyclic voltammetry (CV) measurement indicating that VGs have a very rapid current–voltage response, an excellent electrochemical reversibility and excellent capacitive behavior. The VGs was able to deliver an outstanding specific capacitance value of 345 μF/cm2, and demonstrated an excellent rate capability, which retained 94.41%. Unlabelled Image • Successful preparation of VGs using high-density HWP-CVD for the first time. • Influence of precursor flow rate on the structure and electrochemical properties of VGs was studied. • The growth process of VGs prepared by HWP-CVD was described for the first time. • The microstructure of VGs has been changed to enhance its capacitance and rate capability. • The preparation of VGs by HWP-CVD has a higher capacitance (345 μF/cm2) value and rate capability (94.41%). [ABSTRACT FROM AUTHOR]

3D nitrogen-doped vertically-oriented graphene nanosheets (3D N/VGs) were controllably prepared by helicon wave plasma chemical vapor deposition (HWP-CVD) employing argon, methane, and nitrogen by varying the N 2 flow rate (R N2) without any catalyst and substrate heating during the growth. The effect of plasma gas phase species on the growth structure of N/VGs thin films was studied. The influence of nitrogen doping content on the structure and properties of VGs was analyzed. A growth model for the preparation of N/VGs by HWP-CVD was proposed. The results show that the elevated doping content of nitrogen atoms promotes enhanced CH 4 dissociation and access to more H atoms, leading to an elevated nanosheet number density and a reduced growth rate. More excited N atoms could be embedded into the C vacancy to replace the missing C atom and restore the hexagonal network and increasing the nitrogen content. N/VGs with lower defect densities obtained with enhanced doping of nitrogen. The effective average distance between defects increases with nitrogen content, and the tunneling phenomenon is apparent, increasing resistance. Electrochemical performance tests showed that VGs with high nitrogen atomic content have higher specific capacitance and rate performance, up to 1340 μF/cm2 and 91.7%, respectively. • One step synthesis of N/VGs by CH 4 /N 2 HWP-CVD. • Preparation of N/VGs by doping with controllable N atom concentration. • The doping of N atoms improves the electrochemical performance of VGs. • The substitution of nitrogen atoms for carbon atoms forms C–N bonds, which improves the wall spacing and wall structure size of VGs. [ABSTRACT FROM AUTHOR]