Single material fibers made from low loss material may have excellent optical propagation properties related to absorption loss. Thin film fibers with a convex surface have self focussing properties similar to those of inhomogeneous fibers with quadratic index profile. Such optical waveguides seem to be useful for optical communications and integrated optics. By using the method of conformal mapping, fundamental characteristics of guides modes along optical films with a convex surface are found, and field distributions and dispersions of eigen modes that have not been clarified are shown in detail. These guided modes have Hermite Gaussian field distribution in transverse direction. The spot sizes of guided modes are inversely proportional to the square root of the product of their transverse wave number and the metrical coefficients (1a)l_x, where β₁ and β₂ are phase constants of the material and the guided mode respectively. The factors (1a)l_x derived from mapping function and are quadratic coefficients of the convex surface at the fiber boundaries. The dispersion characteristics of the guided modes are discussed and several numerical examples are presented.

To know the correlation between the surface contamination of semiconductors and electrical properties of semiconductor devices fabricated on the surface, the contamination of chemically etched Si surface was measured by Auger electron spectroscopy (AES) and Schottky contact was formed by evaporation of Au on that surface in situ. The various chemical etchants were used, including HF, HNO₃, CH₃COOH, their mixture, and alkaline etchant. The saturation current, the barrier height, and the n-value of the forward current-voltage characteristics of Au-Si Schottky contact were used for evaluating device characteristics, and in-depth profile of composition of the metal film on Si was also measuring by AES combined with ion-sputter etching. Following results are obtained; The barrier height of the Au-Si Schottky contact whose Si surface is contaminated by carbon is low and 0.810.02 eV, and not far from that of clean surface. On the other hand that of Si surface not so much contaminated by carbon but by oxygen is large and 0.830.01 eV, and the n-value is close to unity. This phenomena can be explained by assuming the vanishing of surface states of Si surface with small oxygen adsorption. This model cannot be applicable to heavily contaminated surface. The results of composition analysis show that a small amount of oxygen passivates Si surface and gives high barrier height.