Optical and structural characteristics of ZnO films grown on (0 0 01) sapphire substrates by ALD using DEZn and N2O

• Published in: Journal of crystal growth 2008-06, Vol.310 (12), p.3024-3028
• Main Authors: LIN, Ping-Yuan, GONG, Jyh-Rong, LI, Ping-Cheng, LIN, Tai-Yuan, LYU, Dong-Yuan, LIN, Der-Yuh, LIN, Hung-Ji, LI, Ta-Ching, CHANG, Kuo-Jen, LIN, Wen-Jen
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Ii-vi semiconductors; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film structure and morphology; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.03.016

Zinc oxide (ZnO) films were grown at 600 deg C on (0 0 0 1) sapphire substrates by atomic layer deposition (ALD) using diethylzinc (DEZn) and nitrous oxide (N2O) as source precursors. In some cases, low-temperature (LT) ZnO buffer layers were employed along with post-annealing or buffer-layer annealing for the optimization of ZnO growth. Based on the theta to 2theta X-ray diffraction (XRD) data, the as-grown ZnO films exhibit a preferred orientation with 0 0 0 1ZnO being parallel to the 0 0 0 1sapphire. Both post-annealing and buffer-layer annealing were found to be very helpful for improving the optical properties of the ZnO films. Room temperature (RT) photoluminescence (PL) spectra of the ZnO films show strong near-band edge (NBE) emissions with completely quenched defect luminescence. The best ZnO films were achieved with a sharp neutral donor excitonic (DoX) emission as well as phonon replicas of free A-excitons in the 10 K PL spectrum.