Improvement of the crystal quality of AlInN by using the patterned sapphire substrate

Lattice-matched (x =0.18) Al_xIn_{1- x}N epilayers were grown on GaN/ patterned sapphire substrate (PSS ) (0 0 0 1) and GaN/ unpatterned sapphire substrate (UPSS) (0 0 0 1) by metal-organic chemical vapor deposition (MOCVD). The quality of the grown AlInN epilayers on the PSS and UPSS were compared. Structural characteristics and surface morphology optical properties of the AlInN epilayers were investigated using double crystal X-ray diffraction (DCXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). It is seen from the DCXRD rocking spectrum that the full width at half maximum (FWHM) of the AlInN grown on PSS was 260 arcsec which is less than UPSS value. The lower value of FWHM indicates that the crystalline quality of the AlInN epilayers grown on PSS is improved compared to AlInN grown on UPSS. It is slso clearly seen from the AFM images that the dislocation density and root mean square (RMS)is less for the AlInN grown on PSS. The above results indicate that the PSS could improve the crystalline and surface morphology greatly.