High-frequency method to determine SiC crystal conductivity

In this paper, we present a simple non-destructive method for testing SiC plate single crystals of any size and shape. The method is based on measuring the impedance changes of an inductive ferrite-cored coil due to placing the sample into the core gap. The method is valid for any SiC polytypes, though we used 6H one. Using this method we have obtained and discussed a conductivity as a function of doping level (N-d-N-a) for 6H-SiC Lely crystals. The conductivity measurements were carried out with alternating current of 747 kHz frequency. The sensitivity of the method is limited by minimal conductivity 1 Omega (-1)cm(-1) (that is corresponding to (N-d-N-a)-2 x 10(16)cm(-3) for 6HSiC:N Lely crystals). (C) 2001 Elsevier Science Ltd. All rights reserved.