Characterization of highly doped n- and p-type 6H-SiC piezoresistors

Highly doped (/spl sim/2/spl times/10/sup 19/ cm/sup -3/) n- and p-type 6H-SiC strain sensing mesa resistors configured in Wheatstone bridge integrated beam transducers were investigated to characterize the piezoresistive and electrical properties. Longitudinal and transverse gauge factors, temperature dependence of resistance, gauge factor (GF), and bridge output voltage were evaluated. For the n-type net doping level of 2/spl times/10/sup 19/ cm/sup -3/ the bridge gauge factor was found to be 15 at room temperature and 8 at 250/spl deg/C. For this doping level, a TCR of -0.24%//spl deg/C and -0.74%//spl deg/C at 100/spl deg/C was obtained for the n- and p-type, respectively. At 250/spl deg/C, the TCR was -0.14%//spl deg/C and -0.34%//spl deg/C, respectively. In both types, for the given doping 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-temperature applications.