摘要： AlN layers of thickness of about 2μm have been grown with AlN nucleation layers (NLs) on (001) sapphire substrates using metal organic chemical vapor deposition. Increasing the AlN-NL deposition temperature from 850 to 1250°C has been found to have significant effect on the surface morphology and the structural quality of the AlN layers. The surface morphology of the AlN-NLs and the AlN layers has been assessed using atomic force microscopy (AFM). The AFM images of the AlN-NLs reveal the coalescence pattern of NLs. AFM images of the AlN layers and the in-situ reflectance measurement disclose the surface morphology and the growth pattern of the AlN layers, respectively. Smooth surface with macro-steps and terrace features has been achieved for the AlN layer grown on the NL deposited at 950°C. The structural quality of AlN layers has been studied by high resolution X-ray diffraction and Raman spectroscopy. The screw dislocation density from (002) reflection and the average edge dislocation density from (102), (302) and (100) reflections of the AlN layer on NL deposited at 950°C are estimated to be 9×107cm−2 and 4.4×109cm−2, respectively. Lateral correlation length (L) is calculated from the (114) reciprocal space mapping of the AlN layers and correlated with the edge dislocation density of the AlN layers. Raman E2 (high) phonon mode indicates compressive strain in the AlN layers grown on the NLs deposited at various temperatures. From this work, it has been inferred that the uniform coalescence of the nucleation islands and the complete coverage of AlN-NL determine the surface morphology and the structural quality of the subsequently grown AlN layers. •Smooth crack-free 2µm thick AlN layers were grown by MOCVD.•In-situ reflectance pattern reveals the redistribution and coalescence of NIs.•Uniformly coalesced islands in the AlN-NL leads to specular surface of AlN.•Deposition temperature and coalescence pattern of NL determines the AlN layer quality. 出版者： Elsevier B.V 出版日期： 2015-03-15 出處： Journal of Crystal Growth, 2015-03, Vol.414, p.69-75 版權： 2014 Elsevier B.V. 識別號： ISSN: 0022-0248 識別號： ISSN: 1873-5002 識別號： EISSN: 1873-5002 識別號： DOI: 10.1016/j.jcrysgro.2014.10.055
