Doping effect on the structure of polycrystalline silicon films grown via silane pyrolysis

X-ray diffraction, transmission and scanning electron microscopy, and secondary-ion mass spectrometry data demonstrate that the grain size, structure, and composition of polycrystalline silicon (poly-Si) films grown using hydride pyrolysis depend on the GeH4 : SiH4 volume ratio in the gas mixture, dopant (boron or phosphorus) concentration, substrate temperature, and heat-treatment temperature. The films grown at substrate temperatures below 600 degrees C are amorphous, and those deposited at 600 degrees C are amorphous-crystalline. Textured poly-Si films are only obtained at 620 degrees C or higher substrate temperatures. Doping with germanium, an isovalent impurity, improves the structural perfection of poly-Si films.