Electrically active defects and dielectric loss in silicon carbide

Data are presented on SiC of various grades for their dielectric loss values at millimeter wavelengths to explore their potential as an alternate material for gyrotron window application. In order to identify the impurities or defects that give rise to the excess loss, temperature-dependent conductivity and DLTS measurements are being undertaken on SiC. Dielectric loss measurements over a wide range of temperatures are in progress to verify the results obtained from electrical methods and help to determine the primary loss mechanisms for SiC in the millimeter wave length range. Experimental results and their implications to loss properties will be discussed.