Analysis of Si1–xGex:H thin films with graded composition and structure by real time spectroscopic ellipsometry



Silicon-germanium (Si1−xGex:H) thin films have been prepared by plasma enhanced chemical vapor deposition of SiH4 and GeH4 and measured during growth using real time spectroscopic ellipsometry. A two-layer virtual interface analysis has been applied to study the structural evolution of Si1−xGex:H films that initially nucleate in the amorphous (a) phase, but evolve to the microcrystalline (μc) phase with accumulated thickness. The compositional evolution of alloy-graded a-Si1−xGex:H has been studied as well using similar methods. Both types of films are of interest for Si-based photovoltaic devices. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)