Polysilicon films with a large mobility can be deposited at tempertures lower than about 400 °C by the catalytic chemical vapor deposition (cat-CVD) Method using a silane and hydrogen gas mixture. The mechanism of polysilicon growth and the structure of polysilicon itself are studied by TEM and X-ray diffraction. It is found that the polysilicon grows from an initial step of the deposition but that the grains start to orient preferentially along a (220) direction as the film grows. It is also found that such preferential axis of the grains is likely to orient toward a heated catalyzer as a sunflower always likes to face the sun.