Materials Science Forum, Vol.353-356, 397-400, 2001
Absorption measurements and doping level evaluation in n-type and p-type 4H-SiC and 6H-SiC
An optical characterization method based on the fundamental absorption bands in SiC is presented for determination of the spatial distribution of doping level concentration in n-type 4H- and 6H-SiC and p-type (Al, B) 6H-SiC. Band gap related absorption has been calculated numerically taking into account band filling, band shrinkage and band tailing effects and has been compared with experimental data. In addition, below band gap absorption transitions in n-type 4H-SiC and p-type (B) 6H-SiC at 460nm and 730nm, respectively, have been investigated. Calibration plots correlating these absorption bands with the charge carrier concentration have been determined and the application for mapping of the doping level distribution in SiC wafers will be demonstrated.