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 Al2O3 by MOVPE (metal-organic vapor phase epitaxy) and the NH3 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 NH3 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 NH3 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 Al2O3. Also, all obtained samples have a sharp absorption edge that shows the quality of the films, but Sample B with 900 sccm NH3 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 NH3 flow are 0.22 nm, 7.86 [ 10(7) , and 1.68 [ 10(10) cm( -2), respectively. The results obtained are comparable to the literature.