In order to completely fill the 50 nm wide high aspect ratio trenches with Cu electroplating, we investigated the influence of barrier metal thicknesses on the voids formation in the trenches. The void occurrence rates were decreased significantly with increasing minimum barrier metal thickness at the side wall of trenches, and it becomes less than 1% when the minimum thickness becomes thicker than 4.6 nm independent of width and aspect ratio of trenches. Resistivities of Cu wires with minimum total barrier metal thickness thicker than 4.6 nm by electroplating, annealing at 573 K for 30 min were found to be almost the same level as those listed in ITRS.
We have studied synthesis condition, mainly heating temperature of precursor and titanic acid, to improve electrochemical property of TiO2(B). TiO2(B) has been prepared from two kinds of Lepidocrocite type Rb0.75Ti1.75Li0.25O4 (Rb-700 or Rb-900) via titanic acid. The cleavage of precursor particles along (0k0) plane during proton exchange was observed for well crystallized precursor heated at 900°C (Rb-900). Chemical composition of titanic acids were expressed as TiO2·0.38H2O, however calculated chemical formula in TiO2·0.29H2O, under assumption of simple ion exchange of Rb+ and Li+ by H+. Titanic acid obtained from Rb-700 formed TiO2(B) in the wider temperature range from 350 to 550°C. TiO2(B) obtained from Rb-700 shows more sloped charge/discharge curve and 1.3 times higher discharge capacity than that from Rb-900. Discharge capacity depends on charge voltage and reaches 300 mAh g−1 at 0.9 V charge. This TiO2(B) also shows excellent rate performance and good coulombic efficiency after 3rd cycles.
Silicon-centered polyoxomolybdate K4[SiMo12O40] (KSM) with the Keggin type structure was investigated as the cathode material for rechargeable lithium battery. The discharge capacity and cycle performance of KSM mainly depends on the annealing temperature. This material shows improved discharge capacity by the increase of annealing temperature. Rietveld analysis of X-ray powder diffraction data and Raman spectra were used to analyze the effect of annealing treatment on the cycle performance of KSM. The results indicate that the improvement of cycle performance would be caused by the re-oxidation of Mo5+ ion in KSM reduced during the preparation process. The KSM cathode shows better electrochemical performance than that of the reported phosphorous-centered polyoxomolybdate K3[PMo12O40] (KPM), indicating that KSM as the cathode material with high discharge capacity and cycle stability is accessible.
The degradation mechanism of humic acids (HAs) by electrolysis in aqueous solutions of Na2SO4 and/or NaCl was examined within a thermodynamics context using potential–pH diagrams. HA degradation is suggested to proceed at the anode through the formation of highly oxidizing sulfuric and chlorine species such as S2O82 - , ClO2 - , and ClO−. In the presence of both SO42 - and Cl− ions, oxidizing chlorine species were found to form preferentially at the anode partly because of the much lower redox potentials of the Cl−/ClO2 - and Cl−/ClO− redox couples compared with that of the SO42 - /S2O82 - redox couple. The change in absorption spectra with time indicated that the degree of HA degradation by S2O82 - ions is higher than that of oxidizing chlorine species, although the degradation rate is much slower. This is attributed to the low formation rate of S2O82 - ions. Linear sweep voltammetry also revealed that the formation of the oxidizing chlorine species was fast and comparable to the rate of O2 generation.
The effect of argon gas condensation (AGC) on crystallinity, surface morphology and photoelectrochemical (PEC) characteristics of SnSe thin films, prepared by thermal vacuum deposition onto ITO/glass substrates, has been investigated. The focal theme was to improve growth process of SnSe thin films and consequently enhance their PEC characteristics, by including argon gas during film manufacturing. For comparison purposes, the films grown With- and Without-AGC were characterized using various techniques such as X-ray diffractometry, UV-VIS spectroscopy, and SEM. The results indicate enhancement in film crystallinity and surface morphology by inclusion of argon gas. Such enhancement has been attributed to slower deposition rate due to argon gas presence. Photoelectrochemical property of SnSe thin film electrodes was studied using linear sweep voltammetry in dark and under illumination. The With-AGC electrodes showed higher photoactivity than the Without-AGC counterparts. Enhancement of PEC characteristics of SnSe With-AGC thin film electrodes is consistent with their crystallinity and surface uniformity. Inclusion of AGC in thermal vacuum deposition processes is potentially valuable to prepare enhanced SnSe thin film electrodes even without the need for further treatment such as etching or annealing.
Fiber-type nickel-hydroxide electrode, namely the Ni(OH)2 layer formed on a nickel-plated carbon fiber, exhibited good high-rate discharge performances. The electrode manufacturing apparatus was developed and several meters of fiber-type electrodes were prepared. An approximate 350 mAh cell using fiber-type electrode exhibited better high-rate discharge performance and lower internal resistance than the conventional paste-type electrode with the equivalent energy density (Ah L−1).