Epitaxial graphene films grown on silicon carbide ͑SiC͒ substrate by solid state graphitization is of great interest for electronic and optoelectronic applications. In this paper, we explore the properties of epitaxial graphene films on 3C-SiC͑111͒/Si͑111͒ substrate. X-ray photoelectron spectroscopy and scanning tunneling microscopy were extensively used to characterize the quality of the few-layer graphene ͑FLG͒ surface. The Raman spectroscopy studies were useful in confirming the graphitic composition and measuring the thickness of the FLG samples.

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The epitaxial growth of GaN/Al 0.5 Ga 0.5 N (11-22) semipolar nanostructures and their structural and optical properties are reported. The nanostructure formation results from a strain induced growth process (Stransky-Krastanov-like growth mode). Atomic force microscopy measurements show that depending on the amount of deposited GaN, the nanostructure shape evolves from an island shape to a string shape aligned along the [1-100] direction. Transmission electron microscopy experiments reveal that (11-20) and (11-23) lateral facets are formed, making with the (11-22) growth plane an angle of 32 and 12 , respectively, and giving a very asymmetric nanostructure shape. Photoluminescence (PL) experiments as a function of the excitation power and temperature show that the internal electric field is very low compared to the case of GaN/Al 0.5 Ga 0.5 N (0001) polar quantum dots (QDs). As a consequence, the PL emission is strongly shifted towards the UV range compared to polar QDs and the full width at half maximum of the PL peak is drastically reduced. Furthermore, a room temperature PL nanostructure emission 300 times more intense than that of the semi-polar GaN template is obtained despite a large density of defects in the surrounding matrix, as expected for efficient carrier localization inside the nanostructures.