Polycrystalline SiC thin films prepared by microwave plasma chemical vapor deposition

The basic properties of silicon carbide (SiC) thin films prepared by microwave plasma chemical vapor deposition were studied. For preparation, monosilane (SiH4) and methane (CH4) were used for source gases, and phosphine (PH3) and diborane (B2H6) were used for doping gases. It was found that the films prepared at the gas-mixing ratio of CH4/SiH4 which ranged from 0.5 to 2.5 are polycrystalline and average grain size is approximately 30nm. The optical energy gap of the SIC films prepared at the gas-mixing ratio of CH4/SiH4 which ranged from 0.75 to 1.5 was almost the same as that of 3C-SiC. The resistivity decreased from 10(3) Omega . cm to 10(1) Omega . cm with increasing the gas-mixing ratio of PH3/SiH4 from 0 to 2%. On the other hand, the resistivity increased from 10(3) Omega . cm to 10(6) Omega . cm with increasing the gas-mixing ratio of B2H6/SiH4 from 0 to 28. The thermistor constant of SIC films prepared at the PH3/SiH4 gas-mixing ratio of 1% was approximately 550.