Papers by Keyword: Raman Mapping

Abstract: We report a new approach to produce high quality epitaxial graphene based on the concept of controlling Si sublimation rate from SiC surface. By putting a mask substrate to suppress Si sublimation from the SiC surface in ultrahigh vacuum, epitaxial graphene growth at 4H-SiC (0001) was locally controlled. Spatially graded surface graphitization was confirmed in a scanning electron microscopy contrast from the outside unmasked region to the inside masked region. The contrast was discussed with Raman characterization as the increase of graphene thickness and the surface compositional change of SiC. Results indicate two types of growth processes of epitaxial graphene at 4H-SiC (0001) step-terrace structures.

Abstract: SLN have shown a great promise as an alternative drug carrier for intravenous and dermal applications. This work focuses on the basic properties of drug-free Compritol^® ATO 888 based SLN systems by using cationic surfactant (CPC) and nonionic surfactant (Tween 80). Effects of surfactant on the physical properties of SLNs were investigated in the absence of model drug to avoid the interaction between drug and surfactant. These SLN samples have different particle size, zeta potential and morphology. DSC was used to quantify the crystallinity of SLN systems. It was found that %RI of both SLNs was similar, indicating that types of surfactant did not affect on crystallization of solid lipid. Spherical-like particle was observed with SLN-C, while rod-like particle was found with SLN-T. The results demonstrated that surfactant plays an important role on SLN physical characteristics.

Abstract: We have studied the application of optical techniques for the determination of the spatial distribution of electronic properties of highly aluminum doped p-type SiC wafers. Absorption and birefringence mapping are known to be sensitive characterization methods to determine the homogeneity of charge carrier concentration and defects in n-type SiC. In the case of highly p-type doped SiC these methods fail due to the opaque character of the material. In this paper we show that Raman spectroscopy which is a reflective method can be used in order to address the same materials properties like absorption and birefringence. The study was performed using medium doped p-type SiC:Al where optical transmission and reflection methods can be applied simultaneously.