Fabrication of Polycrystalline Si_1−xGe_x Films on Oxide for Thin-Film Transistors

Abstract

Polycrystalline-Si1−xGex films have been formed by various methods on oxide-coated Si substrates at temperatures ≤600°C. Compared to thermal growth, plasma deposition of poly-Si1−xGex promotes smoother films with smaller grains having a {200}-dominated texture. Poly-Si1−xGex Alms formed by plasma deposition of amorphous-Si1-xGex followed by a crystallization anneal have an even smoother surface with grain sizes enhanced by an order of magnitude and a weak {111} grain texture. Hydrogen incorporated in amorphous-Si1−xGex evolves completely during crystallization without disrupting the smooth surface morphology. The largest grain sizes (∶1.3μm) are achieved in poly-Si1−xGex films formed by Si+ ion implantation for amorphization with a subsequent recrystallization anneal.

Effects of Ge on Material and Electrical Properties of Polycrystalline Si1 − x Ge x for Thin‐Film Transistors

“…4. 21 The average grain size of undoped poly-Si0.~gGe031 is 0.87 ktm, quite a bit larger than that of undoped poly-Si which is 0.40 p~m for a similar film thickness of 800 A. In fact, poly-Sil_=Ge= films formed by all types of methods investigated had enlarged grain sizes with increased Ge content, as shown in Fig.…”