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

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 alpha-SiC hetero-epitaxial films is considerably reduced to 820 degreesC 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 alpha-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 similar to50 Pa for the following experimental conditions: laser fluence F = 20 J/cm(2)/pulse, distance between a substrate and target d(TS) = 20 mm, and substrate temperature T-S = 820 degreesC. 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. (C) 2003 Elsevier Science B.V. All rights reserved.