We demonstrate 0.8-dB/cm transmission loss for a single-mode, strip Si/SiO(2) waveguide with submicrometer cross-sectional dimensions. We compare the conventional waveguide-fabrication method with two smoothing technologies that we have developed, oxidation smoothing and anisotropic etching. We observe significant reduction of sidewall roughness with our smoothing technologies, which directly results in reduced scattering losses. The rapid increase in the scattering losses as the waveguide dimension is miniaturized, as seen in conventionally fabricated waveguides, is effectively suppressed in the waveguides made with our smoothing technologies. In the oxidation smoothing case, the loss is reduced from 32 dB/cm for the conventional fabrication method to 0.8 dB/cm for the single-mode waveguide width of 0.5 microm . This is to our knowledge the smallest reported loss for a high-index-difference system such as a Si/SiO(2) strip waveguide.

We report the results of an experimental study of the correlations between line edge roughness (LER) and aerial image contrast for different lithographies in identical processing conditions. The characterization has been performed using atomic force microscopy carbon nanotube tips to image the top and bottom of trenches with very high resolution. Experimental results generally support that higher aerial image contrast leads to lower line edge roughness, but differences exist among the lithographies and resists. Top surface roughness results show similar trends with LER. Higher aerial image modulation also yields higher resist sidewall angle.

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Despite the increasing attention paid to the role of working memory in reading, findings and measurement of working memory have been inconsistent. The current meta-analysis aims to provide a quantitative description of the overall relationship between second language (L2) reading comprehension and working memory measured through reading span task and identify methodological features that moderate this relationship. Following a comprehensive search, 25 primary studies (23 peer-reviewed studies and 2 dissertations) were included comprising 37 unique samples (N = 2,682), all of which were coded for substantive and methodological features. The results showed that (a) there is a moderate relationship between L2 reading comprehension and working memory (r = .30), (b) reading span task features such as the scoring procedure, task language, and final word recall order moderate this relationship, and (c) the degree to which working memory’s involvement in L2 reading comprehension may vary depending on the type of reading tasks at hand. Implications are discussed in terms of conceptualization and measurement of working memory. Future directions are also offered in relation to measurement practices to encourage consistency and to improve our understanding of the link between working memory and L2 reading comprehension.

R eading comprehension is a multifaceted process that requires intricate interaction among multiple skills and factors. Background knowledge is a well-known factor that influences