The (100) oriented BaxRb1-xBiO3 (BRBO) thin films were prepared on MgO (100) and SrTiO3(100) (STO(100)) substrate by molecular beam epitaxy using distilled ozone. The (100)-oriented BRBO thin film deposited on STO(100) substrate, showed onset superconducting transition temperature (Tc(onset)) value of 28 K and zero-resistance superconducting transition temperature (Tc(0)) value of 26 K. The respective values for Tc(onset) and Tc(0) of BRBO thin film on MgO(100) substrate were 21 K and 19 K. The growth process of the BRBO thin films grown on MgO(100) and STO(100) substrates were studied by the atomic force microscope (AFM) and the X-ray photoelectron spectroscopy (XPS). Difference in XPS-intensity of Ba as a function of the average thickness for the BRBO thin films deposited on STO(100) substrate and on MgO(100) substrate were observed. The electrical properties of junction using the BRBO thin film and the Nb-doped STO substrate (BRBO/STO(Nb)) was also investigated. The results of the current-voltage measurement and the capacitance-voltage measurement revealed that it is not necessary to take into account the unknown dielectric layer at the interface of BRBO/STO (Nb). It was not possible to interpret well the resistance-temperature behavior of Rb-doped-BaBiO3 thin film (semiconducting BBO(Rb) thin film) with the help of hopping model.

We developed a 1200 dots-per-inch light emitting diode array (1200 dpi LED array) chip using a GaAs0.8 P0.2 epitaxial substrate for the first time. One LED array chip consists of 256 LEDs. In general, LED arrays are fabricated by vapor-phase zinc diffusion. From the viewpoint that shallow junctions should be formed to fabricate a very high-density LED array, solid-phase diffusion seems to be more suitable. We fabricated the LED array using selectively-masked solid-phase zinc diffusion, and the diffusion depth was controlled at 1 µm. The diffusion depth was uniform under the diffusion window. The ratio of the length of lateral diffusion to the diffusion depth was about 1.7. These features imply that Zn diffusion was well controlled. In the Zn diffusion, the carrier concentration in the Zn diffusion region was high enough and the sheet resistance of the diffusion region with a diffusion depth of 1 µm was low enough to obtain a sufficient level of emitted light power. The results of performance tests showed that the characteristics of the LED array chip are satisfactory for application in optical printer print heads, because of the array's highly-resolved near-field pattern characteristic, ample emitted light power, low emitted-light-power deviation, and long life.