LASER-INDUCED SELECTIVE CRYSTALLIZATION OF A-SiGe FILM

Abstract

Laser induced pattern crystallization technique with pulsed KrF excimer (248 nm) laser was used to irradiation amorphous SiGe films prepared by plasma-enhanced chemical vapor deposition (PECVD) on Si substrates. The surface of laser treated sample was investigated by scanning electron microscopy (SEM), it was found that the film irradiated by KrF excimer composed by well-shaped square periodicity embedded in the a-SiGe matrix, and in each square there are laser induced SiGe nanocrystals. The size of SiGe crystals was estimated to be about 10 nm. The samples were analyzed by X-ray diffraction, Raman spectroscopy and photoluminescence analysis before and after crystallization. The Raman spectrum shows strong Ge-Ge, Si-Ge, and Si-Si vibrations that agree with those of crystalline Si 1-x Ge x alloy. Strong PL with two peaks at 720 nm and 750 nm was observed at room temperature in the crystallized film, whereas the uncrystallized sample emits no peaks. These results indicate that nanometer SiGe alloy were formed and laser-induced technology is an efficient technique to produce nanometer materials.