| 초록 |
The physical and electronic characteristics of graphene film significantly vary with its number of layers, and thus the rapid and accurate estimation of the number of graphene layers is essentially required in practical applications as well as in fundamental studies. To date many efforts have been devoted to this issue and several methods based on transmission electron microscopy, atomic force microscopy, Raman spectroscopy, optical microscopy, etc., are now available. Among these, an optical method, in particular based on relative luminance, is a fast, simple and nondestructive technique. However, it still suffers from certain drawbacks that (1) only the central region (central ~30%) of optical image is able to be used for the analysis due to the variation in the light intensity and (2) the sensitivity of discerning the number of graphene layers (i.e., the change in relative luminance with increasing number of graphene layers) is relatively low, causing difficulty in exactly identifying the number of graphene layers. These drawbacks certainly restrict the effectiveness of this method. In this study, therefore, we attempted to resolve these drawbacks by combining a CCD camera with a wide field of view and functionalized optical techniques such as a differential interference contrast technique and polarization technique. |
