Microstructural evolution of high quality AlN grown by PAMBE under different growth conditions.

We have explored the role of growth temperature as well as Al/N flux ratio on the microstructural evolution of high quality AlN grown by Plasma Assisted Molecular Beam Epitaxy. During the transformation process of AlN, lowest full widths at half maximum value of 15 arcmin has been achieved corresponding to lowest screw dislocation density of 8.5 × 108 cm−2. The results determine that AlN films with such low dislocation density can be fruitful as a buffer layer for various III-Nitride structures along with several optoelectronic applications like laser diodes, vacuum UV photodetectors, etc. • Investigated the role of growth temperature & Al/N flux on AlN microstructures. • Realized the lowest FWHM value of 15 arcmin for AlN grown on Si (1 1 1) substrate. • Significantly reduced screw dislocations up to 8.5 × 108 cm−2. • Examined the interplay between temperature & N 2 flow for eliminating metallic Al. The morphological evolution of AlN microstructures by varying the growth temperature and Al/N flux ratio on Si (1 1 1) substrate via plasma-assisted molecular beam epitaxy has been investigated. The transformations in microstructures of AlN grown along the c-plane were explored as a function of N 2 -flow rate, growth temperature and Al-flux. The structural analysis carried out using high resolution X-ray diffraction reveals single crystalline quality with reduced full widths at half maximum value of 15 arcmin corresponding to a screw dislocation density of 8.5 × 108 cm−2. The topographical study of AlN grown by modulating growth conditions revealed an average surface roughness of 6.9 nm. It was exemplified that interplay between higher growth temperature and nitrogen flow rate is desired to prevent condensation of metallic Al on the surface. Also, the AlN pertaining less screw dislocation density leads to lower dark current which can be fruitful for various optoelectronic applications like vacuum-UV photodetectors. [ABSTRACT FROM AUTHOR]