Study on the structural and optic-electronical properties of 4H polytype-SiC films
4H-SiC纳米薄膜的微结构及其光电性质研究

Nanocrystalline (nc) 4H-silicon carbide (SiC) films were deposited by plasma-enhanced chemical vapour deposition,which anode reaction structure was redesigned,with high power density,high hydrogen dilution,pre-bias treatment,bias and low reaction pressure.The crystallization of nc-4H-SiC films could be ascribed to the above conditions,which form bi-flow of plasma on the substrate and make the probability of forming SiC nuclei large,i.e.,the function of forming nulei become strong.High hydrogen plasma etch weak,distorted bonds and amorphous Si_C,Si_Si and Si_H bonds,meanwhile the growth organized-self of nc-4H-SiC films was produced due to difference of etching different bonds.The test results of Raman spectroscopy and high resolution transmission electron microscope (TEM) indicates that the structure of nanocrystalline silicon carbide in films is for hexagonal polytype,i.e.,alpha silicon carbide.The micro-structure of films is two phases structure the nanocrystalline SiC surrounded by amorphous SiC,the mean diameter of micro-columnar nc-SiC is about 16nm.To form the nc-SiC,the pre-bias treatment must be applied and threshold of power desity of PECVD must be over 2.5W/cm 2.the content of nc-SiC increased with power density above threshold.The conductivity of films increased with strong crystallization.