CHARACTERIZATION OF HIGHLY DOPED N-TYPE AND P-TYPE 6H-SIC PIEZORESISTORS

Highly doped (similar to 2 X 10(19) cm(-3)) n- and p-type 6H-SiC strai n sensing mesa resistors configured in Wheatstone bridge integrated be am transducers were investigated to characterize the piezoresistive an d electrical properties, Longitudinal and transverse gauge factors, te mperature dependence of resistance, gauge factor (GF), and bridge outp ut voltage were evaluated. For the n-type net doping level of 2 x 10(1 9) cm(-3) the bridge gauge factor was found to be 15 at room temperatu re and 8 at 250 degrees C, For this doping level, a TCR of -0.24%/degr ees C and -0.74%/degrees C at 100 degrees C was obtained for the n- an d p-type, respectively, At 250 degrees C, the TCR was -0.14%/degrees C and -0.34%/degrees C, respectively. In both types, for the given dopi ng level, impurity scattering is implied to be the dominant scattering mechanism. The results from this investigation further strengthen the viability of 6H-SiC as a piezoresistive pressure sensor for high-temp erature applications.