Semiconducting transition metal dichalcogenides (TMDCs) have attracted a lot of attention recently, because of their interesting electronic, optical, and mechanical properties. Among large numbers of TMDCs, monolayer of tungsten diselenides (WSe2) is of particular interest since it possesses a direct band gap and tunable charge transport behaviors, which make it suitable for a variety of electronic and optoelectronic applications. Direct synthesis of large domains of monolayer WSe2 and their growth mechanism studies are important steps toward applications of WSe2. Here, we report systematical studies on ambient pressure chemical vapor deposition (CVD) growth of monolayer and few layer WSe2 flakes directly on silica substrates. The WSe2 flakes were characterized using optical microscopy, atomic force microscopy, Raman spectroscopy, and photoluminescence spectroscopy. We investigated how growth parameters, with emphases on growth temperatures and durations, affect the sizes, layer numbers, and shapes of as-grown WSe2 flakes. We also demonstrated that transport properties of CVD-grown monolayer WSe2, similar to mechanically exfoliated samples, can be tuned into either p-type or ambipolar electrical behavior, depending on the types of metal contacts. These results deepen our understandings on the vapor phase growth mechanism of WSe2, and may benefit the uses of these CVD-grown monolayer materials in electronic and optoelectronics.

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Morphological studies of aligned nanofibers scaffolds made of poly(glycerol sebacate)(PGS)/poly(ϵ‐caprolactone)(PCL) blends for application as corneal tissue scaffolds are presented. Parallel conductive bars are used as ground electrode to generate unidirectional nanofibers. Scaffolds have fibers diameter in the range of 550–300 nm. The structural stability and wettability, especially the in vitro degradation rate, of the electrospun scaffolds can be controlled by regulating the blended ratio of the polymers. The results indicate that PGS/PCL nanofiber scaffolds can be considered as ideal candidates for corneal tissue engineering scaffolds. The particular motivation for this work is to engineer a tissue‐like construct that will mimic the stromal tissue of the cornea.

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