Japanese Journal of Applied Physics

ITO films, both before and after annealing, were characterized with various methods. The changes in film characteristics are discussed. RIE etching mechanisms for the unannealed ITO films in three reactive gases (CF₂Cl₂, CF₃Cl, and CF₄) and two diluent gases (N₂ and Ar) were delineated by analyzing and comparing the surface ESCA data with the process results. For undiluted gases, indium is the major component left on the surface, and each gas has its own etch preference for different components. The addition of a diluent into the plasma may change the surface composition as well as the etching mechanisms. To increase the whole film etch rate, each component has to be etched off effectively.

Electrical properties of 16 keV, focused-ion-beam (FIB) (beam diameter: 1 µm, current density: 50 mA/cm²) boron-implanted silicon layers have been investigated as a function of beam scan speed and ion dose, and compared with those obtained by conventional implantation (current density: 0.4 µA/cm²). High electrical activation of the FIB implanted layers is obtained by annealing below 800°C as a result of the increase in amorphous zones created in the implanted layers. Amorphous zone overlapping is assumed to occur at FIB implantation doses of 3–4×10¹⁵ ions/cm² from the results of electrical activation and the carrier profile of implanted regions annealed at low temperature, if beam scan speed is lowered to about 10^-2 cm/s.

Growth of needles induced by positive discharging in air containing a small amount of dimethyl-poly-siloxane (DMPS) vapor was examined. After discharging for 30 to 120 minutes in pure air containing DMPS vapor, amorphous SiO₂ needles and a thin film had grown on tungsten wire anode. The needles had a hollow tube running parallel to the axis of each needle. In contrast, needles grown in just pure air contain tungsten. The growth of needles caused by plasma oxidation of DMPS and by sputtering of the tungsten wire anode owing to negative ion impinging is discussed.

A new method of high resolution electron microscopy utilizing a real time VTR-TV monitor system has been developed for the study of small metal particles less than 100 Å in size. The study for the first time revealed the real time motion of the surface atoms on a 100 Å gold cluster. The particle is a cuboctahedron and its {111} and {100} type surface are viewed as their edge-on projections along the <110 > direction. The surface atomic steps are formed on the {100} type surfaces but not on the {111} surfaces. The steps frequently change their positions within less than one tenth of a second. This motion is direct evidence of the random walk of the surface atoms on metal surfaces.

Distribution coefficients of Nd³⁺, Tm³⁺ and Er³⁺ in calcium niobium gallium garnet (CNGG) single crystals have been investigated. The values of the equilibrium distribution coefficient, k ₀, of Nd³⁺, Tm³⁺ and Er³⁺ in CNGG single crystals have been determined to be 0.55, 1.09 and 1.14, respectively. It is shown that the distribution coefficients of Nd³⁺ in CNGG single crystals are larger than those in other garnet crystals such as Y₃Al₅O₁₂ and Gd₃Ga₅O₁₂. The variation of the k ₀ values is discussed in relation to the ionic radii of each of the cations.

We investigated the effects of intentional sodium incorporation on the electrical conductivity of Cu-poor CuInS₂ thin films. CuInS₂ films were fabricated by sulfurization of In–S/Cu/Na₂S/In precursors. Sodium incorporation resulted in a remarkable increase in the lateral conductivity and the cell efficiency of CuInS₂-based solar cells. Photoluminescence measurements revealed that the enhancements were attributed to the annihilation of donor states, most likely In interstitials, by sodium incorporation.