Fabrication of crystallized boron films by laser ablation

Polycrystalline β-rhombohedral boron films mixed with amorphous boron phase have been successfully fabricated on quartz substrates using pulsed laser ablation in a quartz glass tube chamber placed in an electric furnace. The crystallinity of the films strongly depended on the temperature of the furnace and the pressure of background argon gas. High temperature and high pressure in the chamber were suitable for crystallized boron film preparation. The best crystalline films (without B₂O₃ phase formation) were obtained at 1000°C, 100 Pa. XPS measurements demonstrated that the major contaminants were carbon and oxygen, and the atomic ratio of oxygen to boron was 0.05 under the preparation conditions of well-crystallized films. The surface roughness of the films decreased by lowering laser energy to 150 mJ/pulse under the same pressure and temperature conditions.