Successive segregation in laser-crystallized poly-SiGe thin films

Polycrystalline silicon-germanium (poly-SiGe) thin films on glass substrates, crystallized with multiple number of laser pulses, were characterized with energy dispersive X-ray and Raman spectroscopy. Strong lateral segregation was observed for laser-crystallized poly-Si 1-x Ge x with 0.33 < x < 0.7, causing the local Ge content to differ by as much as 40% from the average value. The segregation manifests itself in the appearance of well-resolved peaks in the Raman phonon modes. It is shown that the segregation in the samples evolves successively with increasing number of laser pulses.