Abstract: Electric parameters including resistivity,mobility,and free carrier concentration are measured at low temperatures for n-type 6H-SiC from China and Cree corporation.Their impurity concentration and levels are obtained from the fitting data of FCCS.The experimental results show that the concentration and compensation level of the impurity greatly affect the electric properties of SiC at low temperatures.The two different levels of nitrogen donor work together for 6H-SiC with a low compensation,but the accepter levels work at low temperatures for 6H-SiC with a high compensation.The peak of the mobility curve of the latter decreases and moves to the right as temperature increases.At the same time,the highly compensated SiC is transformed from n-type to p-type at low temperatures,which is analyzed theoretically.

Key words: free carrier concentration, FCCS, donor, accepter, compensation level, distribution function