Raman study of Epitaxial lateral Overgrowth of GaN on Patterned Sapphire Substrate

Abstract

Structural and optical properties of gallium nitride (GaN) epilayers grown on lens shape patterned sapphire substrate (PSS) using metalorganic chemical vapor deposition (MOCVD) for various growth times were evaluated. From Raman spectra, a blue shift and reduction in the FWHM of Raman modes of GaN grown on PSS were observed when compared to GaN grown on unpatterend sapphire substrate (UPSS). From the DCXRD spectra, full width at half maximum (FWHM) value was decreased with increasing growth time. FWHM of the sample grown at 80 min was 473.5 arc sec. This indicates that there is an improvement in crystalline quality of the GaN grown on PSS as the growth time increases. From photoluminescence (PL) spectra, an increase in band edge emission intensity and a decrease in defect related yellow luminescence were observed for GaN on PSS as the growth time increased.