Characterization of Si-doped GaN on (00.1) sapphire grown by MOCVD

We investigated structural, electrical and optical properties and their relationships for MOCVD grown Si-doped GaN with different doping levels. The changes in structural properties such as strain, crystallinity and strain relaxation as a function of carrier concentrations were measured by high-resolution triple-axis X-ray diffraction and reciprocal space mapping technique. As the carrier concentration of the samples increases from 1.6×10¹⁸ to 9.5×10¹⁸/cm³ Hall mobility decreases from 222 to 170 cm²/Vsec, and peak intensity ratio of band edge to yellow luminescence in photoluminescence spectra decreases too. The variation of mosaic spread along [00.1] direction determined from full width at half maximum (FWHM) of GaN (00.2) peaks shows good agreement with the variation in Hall mobility. In addition, dislocation density determined from FWHM of (10.2) peaks is shown to be related to the variation in the intensity of yellow luminescence in PL spectra.