The off current of amorphous silicon (a-Si: H) thin film transistors (TFTs) depends on fabrication after back-channel etching. Plasma treatment after back-channel etching affects off current in the lower subthreshold voltage region. Off current is high in O2 plasma treatment and low in N2 plasma treatment. Without plasma treatment, off current can not be controlled. N2 plasma treatment affects the interface characteristics between a-Si: H layer and passivation layer, obstructing electron transport near the back-channel inerface.
Current interruption was used to measure silicon dioxide layer capacitance and Si oxidation activation energy at 20∼70°C. A current interrupter was built using an electromagnetic relay and integrated circuits. When Si was anodized in an ethylene glycol solution, the current between the n-type Si wafer anode and Pt cathode was interrupted for 5ms on galvanostatic electrolysis, and the transient phenomena of voltage waveform, form which short term anodic oxidation kinetic parameters are obtained, were observed by a digital memory scope. Oxide film capacitance increased rapidly beyond a current density of 1mA cm-2. Oxide film capacitance increased with electrolyte temperature up to about 40°C, but decreased as temperature increased from 45°C to 50°C. Activation energy for silicon anodic oxidation was about 23.7kJ mol-1 over 55°C and 122kJ mol-1 at 20∼40°C.
Bonding is useful in surface hardening nickel (Ni) in many surface treatments. Although Ni boronized by powder-pack bonding with amorphous boron and by gas bonding with BCl3 has been reported, few reports cover bonding in a fluidized bed. We analyzed the treated layer using X-ray diffraction (XRD), glancing incidence X-ray diffraction, glow discharge emission spectrometry (GDS), and electron probe microanalyzer (EPMA). High-temperature microhardness and friction and wear characteristics of boronized Ni were studied, with the following results: (1) Bonding Ni at a high temperature over a long time in a fluidized bed showed flaking of the treated layer due to Ni siliconization. (2) The Knoop hardness was 1300HK for the sample boronized 7.2ks at 1073K. The boride layer was about 25μm thick and consisted mainly of Ni2B and Ni3B. (3) The high-temperature microhardness of boronized Ni is higher than that of untreated Ni below about 800K. (4) Friction properties and wear resistance to SUJ2 and SUS304 were improved by Ni bonding.
The aluminum surface was modified by CO2 laser beam irradiation onto a surface coated 0.2mm thick with TiO2 powder. Surface and cross sectional views of melted layers formed under different laser irradiating conditions were observed by optical microscope. Cross-sectional hardness was evaluated by micro-Vickers hardness measurement, and the composition was studied by microdiffraction analysis. A hard alloyed layer formed on the surface of the Al substrate at laser power exceeding 2kW. At less than 2kW, a clad layer formed. The alloyed layer consists of eutectic Al+Al3Ti. Hardening in the alloyed layer is caused by crystallization of the Al3Ti intermetallic compound formed by a reaction between substrate Al and Ti separated from TiO2. TiO2 powder is thus useful in laser alloying.
Based on the results of previous single complexing agents, we prepared mixed complexing agents for electroless NiB plating based on sodium citrate, and studied their characteristics. Complexing agents were mixed as follows: sodium citrate-sodium malonate, sodium citrate-glycine, sodium citrate-diethylenetriamine. The deposition rate from the mixed complexing agent bath was influenced by pH and complexing agent concentration, and mainly corresponded to mixed behavior except for sodium citrate-diethylenetriamine. The boron content of deposited films gradually increased with increasing sodium citrate concentration for the mixed complexing agent. The carbon content was highest as 0.72wt% at a ratio of 1:1 for sodium citrate-diethylenetriamine. The microstructure and crystallization by heat-treatment of NiB films mainly depended on boron content for the mixed system. Codeposited carbon in NiB films may also affect the microstructure and crystallization behavior.
Cyclic voltammetry and a quartz crystal microbalance were used to study hydrogen adsorption in a sulfuric acid solution under magnetic field and in magnetically treated electrolyte. These conditions suppressed hydrogen adsorption. The exchange ratio of adsorbed hydrogen to desorbed sulfate anions was evaluated by the ratio of mass change to cathodic charge. We confirmed that the ratio of adsorbed hydrogen to desorbed sulfate anions was controlled by the magnetic effect.