Influence of argon gas pressure on the crystallinity of α-SiC epitaxial films fabricated by Nd:YAG pulsed-laser deposition

Abstract

Abstract Fabrication of SiC crystalline films at low temperatures is examined by pulsed-laser deposition (PLD), since it is important for SiC device technology. The growth temperature of α-SiC hetero-epitaxial films is considerably reduced to 820 °C by fabricating under argon (Ar) atmosphere using a very high fluence of the fourth harmonics of Nd:YAG laser. Influence of the Ar gas pressure on the crystallinity of α-SiC film is studied with X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED). It is found that the optimal pressure is critical and is ∼50 Pa for the following experimental conditions: laser fluence F=20 J/cm2/pulse, distance between a substrate and target dTS=20 mm, and substrate temperature TS=820 °C. Under lower pressure than 40 Pa, the film becomes amorphous. On the other hands, higher pressure than 50 Pa results in poly-crystalline films. These results are plausibly explained by the high kinetic energy of ejected species by laser ablation with high fluence and their collision with the atmospheric Ar gas atoms.