Orientation control of α-Al₂O₃ films prepared by laser chemical vapor deposition using a diode laser

(006)-, (104)- and (012)-oriented α-Al₂O₃ films in a single phase were prepared by laser chemical vapor deposition (LCVD) using a diode laser. The effects of laser power (P_L), deposition temperature (T_dep) and total pressure (P_tot) on the crystal phase, orientation, microstructure and deposition rate (R_dep) were investigated. The orientation of α-Al₂O₃ films changed from (006) to (104) to (012) with increasing P_L. Higher oriented films were deposited at a lower P_tot. The microstructure of α-Al₂O₃ films changed from a cauliflower-like structure to a hexagonal faceted structure to a pyramid-like structure with increasing P_L. The R_dep of oriented α-Al ₂O₃ films slightly increased from 30 to 40μm·h^-1 with decreasing P^L, which was about 50 times greater than that of conventional thermal CVD.