Epitaxial Growth of Fe3O4 Layers on the C-Plane of Sapphire by Pulsed Laser Deposition

Abstract

We have studied the effect of substrate temperature and molecular oxygen pressure on the growth of thin (<180 nm) epitaxial Fe₃O₄(111) films on the C-plane of single-crystal sapphire (Al₂O₃(0001)) via pulsed laser evaporation. We have investigated the electrical properties, morphology, and structure of magnetite films grown under various conditions and the magnetic-field and temperature dependences of their resistivity. Fe₃O₄ has been shown to have a stable growth plateau (SGP) at pressures in the range (3–9) × 10^–5 Torr and growth temperatures from 300 to 550°C. With increasing growth temperature, the SGP shifts to higher oxygen pressures. Analysis of the effect of film growth temperature indicates that optimal electrical characteristics and a more perfect crystal structure are ensured by elevated growth temperatures, above 400°C, whereas growth temperatures below 350°C make it possible to minimize the surface roughness of the films and improve their surface homogeneity. Annealing magnetite films under high vacuum above the growth temperature allows all of these requirements to be met.