Epitaxial CuO thin films prepared on MgAl2O4 (110) by RF-plasma assisted pulsed laser deposition

Abstract CuO films were deposited on MgAl2O4 (110) substrates by pulsed laser deposition. The structural and optical properties of the films prepared at different oxygen plasma pressures were investigated. The film prepared at 0.2 Pa was pure CuO having the best film crystallinity and an out-of-plane epitaxial relationship of CuO (010)∥MgAl2O4 (110). Two different kinds of domain structure were observed for the 0.2 Pa-deposited sample and the corresponding in-plane epitaxial relationships were deduced to be CuO [10 1 ¯ ]∥MgAl2O4 [001] and CuO [101]∥MgAl2O4 [001]. A schematic diagram was proposed to clarify the growth mechanism. The optical band gap of the as-prepared copper oxide films varied from 1.14 to 1.47 eV. Our study indicates the feasibility of epitaxial growth of monoclinic CuO films on cubic MgAl2O4 substrates.