Effects of corundum-structured seeds on the low-temperature growth and hardness of the alumina-based films

Abstract

The corundum-structured seeds have been introduced into alumina films using Al + α -Al _2 O _3 composite and Al _100−x Cr _x (x = 10, 20, 30) alloy as targets by reactive magnetron sputtering. The effects of the seeds on the elemental composition, phase composition, structure characteristic, surface morphology and nano-hardness of the alumina-based films have been investigated. The Al target has also been sputtered to prepare the alumina film as reference. The film is composed of single-phase α -Al _2 O _3 by sputtering the Al + α -Al _2 O _3 composite target at 550 °C, while the solid solution α -type (Al _0.7 Cr _0.3 ) _2 O _3 was detected in the film prepared with the Al _70 Cr _30 target at the same temperature. The nano-hardness of the pure α -Al _2 O _3 film and the α -(Al _0.7 Cr _0.3 ) _2 O _3 film were measured as ∼23.5 GPa and ∼28.5 GPa, respectively, which are much higher than that of the film deposited from Al target (∼16.3 GPa).

Keywords

• corundum-structured seed
• alumina-based film
• composite target
• low temperature
• depth-sensing indentation