High-quality AlN growth: a detailed study on ammonia flow

High crystalline and optical quality aluminum nitride (AlN) films with thin thickness have been grown on Al 2 O 3 by MOVPE (metal-organic vapor phase epitaxy) and the NH 3 flow rate has been changed to improve the morphology and quality of the films. Some characterization types of equipment such as atomic force microscopy (AFM), high-resolution X-ray diffraction (HRXRD), and Raman spectroscopy have been carried out to investigate the effect of different NH 3 flow rates on surface morphology, roughness, and crystal quality of AlN, respectively. Unlike in the literature, in situ optical reflectance measurements have been given depending on NH 3 flow rate and optical characterization has been performed by UV–VIS–NIR spectrophotometry. The well-defined interference patterns in the optical transmittance graph report a sharp interface between AlN and Al 2 O 3 . Also, all obtained samples have a sharp absorption edge that shows the quality of the films, but Sample B with 900 sccm NH 3 flow has the sharpest absorption edge because it has high optical quality and low defect. The RMS (root mean square), D S (screw-type dislocation density), and D E (edge-type dislocation density) values of AlN with 900 sccm NH 3 flow are 0.22 nm, 7.86 х 10 7 , and 1.68 х 10 10 cm −2 , respectively. The results obtained are comparable to the literature.