X-ray Absorption Fine-Structure and Optical Studies of AlZnO Nano- Thin Films Grown on Sapphire by Pulsed Laser Deposition

摘要

Al-doped ZnO can replace tin-doped indium oxide (ITO) as a good transparent conductive oxide (TCO) in LEDs and optoelectronic applications. We investigate on nanometer scale AlZnO thin film materials epitaxied on sapphire substrates in 350-650℃ from pulsed laser deposition (PLD). Synchrotron radiation X-ray absorption fine-structure spectroscopy on O K-edge indicates that Al-doped ZnO can not form alloy at growth temperature 350℃ without Al-O bonding feature. The Al-0 transition of AZO550 is stronger than AZO650. These are correlated to Raman scattering measurements and analyses. Al-doped ZnO grown at 350℃ possesses weak/broad Raman signals indicating a poor crystalline film. The E_2 (high) mode is strong and narrow in AZO550. All these experimental results indicate that PLD grown AlZnO film on sapphire could get a better crystalline quality at 550℃ than 350℃ and 650℃.