Hirokazu Izumi

Electrical and structural properties of indium tin oxide films prepared by pulsed laser deposition

The relation between electrical and structural properties of indium tin oxide (ITO) films prepared by pulsed laser deposition with and without in situ laser irradiation is examined. The residual stresses of the films were estimated from x-ray diffraction patterns measured by grazing-incidence asymmetric Bragg and grazing-incidence x-ray diffraction geometries. For the films prepared without in situ irradiation, the residual stress depended on oxygen pressure (PO2) during deposition and had minimum around PO2 of 1.3 Pa, which coincided with the optimum PO2 for growing the lowest resistivity films. The resistivity was only slightly improved with an increase of substrate temperature (Ts) because a large residual stress was introduced. In contrast, the ITO films prepared with in situ laser irradiation showed very low resistivity (ρ<10−4 Ω cm) which can be attributed to the high crystallinity and low residual stress.

Pulsed Laser Deposition of Low-Resistivity Indium Tin Oxide Thin Films at Low Substrate Temperature

Indium tin oxide (ITO) thin films were grown on SiO2 glass and silicon (Si) substrates from a 95 wt% In2O3–5 wt% SnO2 sintered ceramic target by pulsed laser deposition (PLD). The films were deposited under different oxygen pressures (Po2) of 5×10-3 to 5×10-2 Torr at room temperature (RT) and 200°C. Po2 was found to have a critical influence on the optical and the electrical properties of the ITO films. Under a Po2 of 1×10-2 Torr, ITO films with resistivity as low as 4.5×10-4 and 1.8×10-4 Ωcm were obtained on glass at RT and 200°C, respectively. Moreover, by increasing the substrate temperature (Ts) to 350°C, the resistivity was further reduced to 1.3×10-4 Ωcm. Optical transmittance in visible light greater than 85% was attained in all the films deposited under Po2 above 5× 10-3 Torr. However, a reduction in the transmittance to less than 80% was observed as Po2 decreased. The films deposited at RT were amorphous, whereas those produced at 200°C were polycrystalline.

Electrical properties of crystalline ITO films prepared at room temperature by pulsed laser deposition on plastic substrates

Electrical properties of crystalline indium-tin-oxide (ITO) films, which were grown on polycarbonate (PC) substrates at room temperature by pulsed laser deposition (PLD) with in situ laser irradiation onto the substrates, were studied. The PC substrates were colored by in situ laser irradiation when the ITO films were prepared on the substrates directly, and the resistivity of the ITO films was extremely high. While the PC substrates were prevented from coloring by pre-deposition of CeO 2 film, the resistivity was still high. The introduction of a thin Al 2 O 3 layer between the PC substrate and CeO 2 film resulted in marked decreasing of the resistivity of the ITO film.

Highly conducting indium tin oxide (ITO) thin films deposited by pulsed laser ablation

Abstract Highly conducting and transparent indium tin oxide (ITO) thin films were prepared on SiO2 glass and silicon substrates by pulsed laser ablation (PLA) from a 90 wt.% In2O3-10 wt.% SnO2 sintered ceramic target. The growths of ITO films under different oxygen pressures (PO2) ranging from 1×10 −4 –5×10 −2 Torr at low substrate temperatures (Ts) between room temperature (RT) and 200°C were investigated. The opto-electrical properties of the films were found to be strongly dependent on the PO2 during the film deposition. Under a PO2 of 1×10 −2 Torr, ITO films with low resistivity of 5.35×10 −4 and 1.75×10 −4 Ω cm were obtained at RT (25°C) and 200°C, respectively. The films exhibited high carrier density and reasonably high Hall mobility at the optimal PO2 region of 1×10 −2 to 1.5×10 −2 Torr. Optical transmittance in excess of 87% in the visible region of the solar spectrum was displayed by the films deposited at P o 2 ≥1×10 −2 Torr and it was significantly reduced as the PO2 decreases.

HIGH-QUALITY INDIUM OXIDE FILMS AT LOW SUBSTRATE TEMPERATURE

Low-resistivity (ρ) and highly transparent pure indium oxide (In2O3) thin films grown on glass substrates by pulsed laser deposition at substrate temperature (Ts) between room temperature and 200 °C are reported. As-deposited films with resistivity (ρ) of ∼3×10−4 Ω cm and transmittance (visible), above 87% were obtained within a narrow range of PO2 (1×10−2–1.5×10−2 Torr). Hall effect measurements showed that the low ρ resulted from the high carrier concentration (n)∼7×1020 cm−3, whereas modest Hall mobility (μ<45 cm2 V−1 s−1) was measured. X-ray diffraction indicated that the films prepared at Ts⩽100 °C were amorphous, while at Ts⩾150 °C polycrystalline films were obtained.

Effect of Sn doping on the electronic transport mechanism of indium–tin–oxide films grown by pulsed laser deposition coupled with substrate irradiation

Low-resistivity indium–tin–oxide (ITO) films (8.9×10−5–2.3×10−4 Ω cm), 80±20 nm thick grown by combining pulsed laser deposition and laser irradiation of the substrate were studied in relation to tin (Sn) doping content. Films with Sn doping content over the range 0–10 wt % were deposited at room temperature (RT) and 200 °C at a fixed oxygen pressure of 1×10−2 Torr. The laser beam with energy density of 70 mJ/cm2 was directed at the middle portion of the substrate during growth. At RT, the laser-irradiated and nonirradiated parts of the films exhibited crystalline and amorphous phase, respectively. The amorphous films indicated a steady resistivity, carrier concentration, and Hall mobility of ∼2.4×10−4 Ω cm, 8×1020 cm−3, and ∼32 cm2/V s, respectively, and showed no significant change over 0–10 wt % Sn doping content. The crystalline films deposited at RT by laser irradiation and 200 °C indicated a strong dependence of the resistivity, carrier concentration, and Hall mobility on Sn doping content over the ...

High-Performance Characteristics of Bonded Magnets Produced Using Sm2Fe17Nx Powder Stabilized by Photoinduced Zinc Metal Coating

The surface of Sm2Fe17Nx fine powder was stabilized by coating with zinc metal produced by the photodecomposition of diethylzinc (Zn(C2H5)2). The remanence (B r) and coercivity (H cj) values of the resulting Zn/Sm2Fe17Nx powder were changed little by zinc coating, and remained at high levels even after heat treatment at 423 K, since the oxidation-resistance was improved by the zinc coating. Epoxy resin bonded magnets prepared using the Zn/Sm2Fe17Nx powder had a maximum energy product ( BHmax) value of 176 kJm-3, which did not change greatly after exposure to air. The irreversible flux loss of the bonded Zn/Sm2Fe17Nx magnet was smaller than that of the uncoated Sm2Fe17Nx magnet.

Effective Grinding Procedure for Sm2Fe17Nx Powder with High-Performance Permanent Magnetic Characteristics.

Finely and uniformly ground powder samples (mean particle size <3 µ m) of Sm2Fe17Nx (x= approx. 3.0) which were obtained by ball milling in hexane solution containing a surface-active agent for 1-3 days, provided high remanence (B r) and coercivity ( iH c) values: B r=1.2-1.3 T and iH c=0.9-1.1 MA m-1 (11-14 kOe), although their mean particle size (<3 µ m) was still larger than that of the calculated one for the single magnetic domain (~0.3 µ m). These excellent magnetic characteristics were attributed to size uniformity, surface smoothness, and less strain induced in the finely ground powder particles.

Pulsed Laser Deposition of Crystalline Indium Tin Oxide Films at Room Temperature by Substrate Laser Irradiation

Crystalline tin (Sn)-doped indium oxide (ITO) films grown at room temperature (RT) using pulsed laser deposition (PLD) coupled with laser irradiation of the growing films are discussed. The energy of the laser irradiation beam was ~0.07 Jcm-2. The films were deposited from Sn-doped (0–10 wt%) In2O3 targets under oxygen pressure (PO2 ) of 10-2 Torr. At RT, the laser-irradiated and nonirradiated portions of the films yielded resistivities of ~1.2×10-4 and ~2.5×10-4 Ωcm, respectively. At 200°C, a resistivity of 8.9×10-5 Ωcm was observed for the laser-irradiated part of the ITO films.

Particle size dependence of the magnetic properties for zinc-coated Sm2(Fe0.9Co0.1)17N2.9 powders

Abstract By adjusting the mean powder particle size of the Sm2(Fe0.9Co0.1)17N2.9 compound, high-performance magnetic powders with a (BH)max value of 46.8 MGOe (371 kJ m−3) were prepared by ball milling in an organic solution containing surface active agent. The subsequent zinc-coating process allowed the powders to be stabilized against oxidation by O2 or H2O. The above two steps were optimized by investigating the powder grain size (milling time) dependence of the zinc-treatment efficiency.