Low-temperature deposition of highly crystallized silicon films on Al-coated polyethylene napthalate by inductively coupled plasma CVD

We prepared highly crystallized silicon films on Al-coated polyethylene napthalate (PEN) substrates using inductively coupled plasma chemical vapor deposition (ICP-CVD) at low temperature with a mixture of SiH4/H2 as the source gas. The microstructure of the films was evaluated using Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The effects of deposition parameters on the crystallinity of silicon films on bare and Al-coated PEN were systematically investigated. Compared to the films deposited on bare PEN, an obvious phase transition from amorphous to crystalline occurred when decreasing the SiH4 dilution ratio [R = [SiH4]/([SiH4] + [H2])] to 4% for the films on Al-coated substrates. With increasing the input power from 300 W to 400 W, the crystallinity of the films on bare and Al-coated PEN are both improved at a low temperature as low as 85 °C. The film on Al-coated PEN shows excellent crystallization with crystalline fraction of 82% and preferred orientation of (1 1 1). It has been found that the interaction between precursors and aluminum layers plays an important role and there should exist a different crystallization mechanism as compared to traditional annealing crystallization of amorphous Si/Al layer in the crystallization process of silicon films on Al-coated PEN at low temperature.