Yukako Hayashi

Transparent conducting amorphous Zn–Sn–O films deposited by simultaneous dc sputtering

The films of ZnO–SnO2 system were deposited on glass substrates by simultaneous dc magnetron sputtering apparatus, in which ZnO and SnO2:Sb (Sb2O5 3 wt % doped) targets faced each other. The substrate temperatures were maintained at 150, 250, and 350 °C, respectively. As an experimental parameter, current ratio δ=IZn/(IZn+ISn), which corresponds to ZnO target current (IZn) divided by the sum of ZnO and SnO2:Sb target currents (IZn+ISn), was adopted. Amorphous transparent films appeared for 0.50⩽δ⩽0.73, which could be correlated to compositions as [Zn]/([Sn]+[Zn])=0.33–0.67 by x-ray fluorescent analysis. At [Zn]/([Sn]+[Zn])=1/2 (δ=0.62), 2/3 (δ=0.73) and all other ratios in as-deposited films, neither crystalline ZnSnO3 nor Zn2SnO4 was obtained. Minimum resistivity of 4–6×10−2 Ω cm was found at δ=0.50, whose composition was approximately SnO2⋅ZnSnO3. Resistivity increased linearly with an increase of the current ratio, until the composition reached Zn2SnO4. The amorphous phase showed a constant Hall mobili...

Amorphous transparent conductive oxide films of In2O3-ZnO with additional Al2O3 impurities

Al-doped In2O3-ZnO films were developed and the influence of Al doping in electrical and optical properties of In2O3-ZnO films was investigated. Amorphous and homologous phases appeared with increasing δ=Zn∕(Zn+In) ratios. The carrier generation mechanism is discussed for these films. Native oxygen defects are the primary donors for the In2O3-ZnO films. Then the low resistivities of 2–4×10−4Ωcm were attained within a narrow range of δ=Zn∕(Zn+In) in the amorphous phase film. Two wt % (percent by weight) Al2O3-doping decreased the resistivity to 1.5–2.1×10−4Ωcm. At doping of 3 and 4 wt % Al2O3, film resistivities of 2–4×10−4Ωcm were attained for a relatively wide range of δ in the amorphous phase due to an increase in carrier concentration at δ=0.3–0.6. However, Al2O3 doping in homologous phase In2O3-ZnO films decreased carrier concentration independently of the levels of Al2O3 doping. Al2O3 doped in the homologous ZnkIn2Ok+3 crystalline films did not act as a donor impurity. The optical band-gap energy for...

Kinetic and ESR studies on radical copolymerization of p‐tert‐butoxystyrene and di‐n‐butyl maleate in benzene

The copolymerization of p-tert-butoxystyrene (TBOSt) (M1) and di-n-butyl maleate (DBM) (M2) with dimethyl 2,2′-azobisisobutyrate (MAIB) in benzene at 60°C was studied kinetically and by means of ESR spectroscopy. The monomer reactivity ratios were determined to be r1 = 2.3 and r2 = 0 by a curve-fitting method. The copolymerization system was found to involve ESR-observable propagating polymer radicals under practical copolymerization conditions. The apparent rate constants of propagation (kp) and termination (kt) at different feed compositions were determined by ESR. From the relationship of kp and f1 (f1 = [M1]/([M1] + [M2])) based on a penultimate model, the rate constants of five propagations of copolymerization were evaluated as follows; k111 = 140 L/mol s, k211 = 3.5 L/mol s, k112 = 61 L/mol s, k212 = 1.5 L/mol s, and k121 = 69 L/mol s. Thus, a pronounced penultimate effect was predicted in the copolymerization.

(Liquid + liquid) equilibria of (water + ethanol + 2,6-dimethyl-4-heptanone) from 0.1 to 200 MPa at 298.15 and 323.15 K

Abstract Experimental tie-line measurements were made on (water + ethanol + 2,6-dimethyl-4-heptanone) in the range 0.1 to 200 MPa at 298.15 and 323.15 K. The binodal curves obtained show that the immiscibility region is little affected by pressure, but contracts slightly at elevated temperatures. As the temperature and the pressure rise, the plait point shifts towards the aqueous phase at lower mole fraction of ethanol and towards the organic phase at higher mole fraction of ethanol, respectively. The variations of the tie-line and of the distribution curve of ethanol with temperature are opposite in direction to those with pressure. The distribution coefficient D2 of ethanol depends on temperature and pressure, but weakly on the mole fraction of ethanol in the organic phase, except near the plait point. The tie lines were satisfactorily correlated by the Othmer-Tobias equation on a mass-fraction basis.

Annealing Effects on Transparent Conducting Properties of Amorphous ZnO-In2O3 Films

Structural and transparent conducting properties of amorphous Zn-In-O films deposited by simultaneous sputtering of ZnO and In2O3 targets facing each other were reviewed. Post-annealing under the reductive gas flow was effective on improving unevenness of the amorphous films.