The wide bandgap energy and low intrinsic carrier concentration of SiC allow SiC to maintain
semiconductor behavior at much higher temperatures than silicon, which in turn permits SiC semiconductor
device functionality at much higher temperatures than silicon . As discussed in basic
semiconductor electronic device physics textbooks, semiconductor electronic devices function
in the temperature range where intrinsic carriers are negligible so that conductivity is controlled by
intentionally introduced dopant impurities. Furthermore, the intrinsic carrier concentration
is a fundamental prefactor to well-known equations governing undesired junction reverse-bias leakage
currents. As temperature increases, intrinsic carriers increase exponentially so that undesired leakage
currents grow unacceptably large, and eventually at still higher temperatures, the semiconductor
device operation is overcome by uncontrolled conductivity as intrinsic carriers exceed intentional
device dopings. Depending upon specific device design, the intrinsic carrier concentration of silicon
generally confines silicon device operation to junction temperatures <300°C. SiC’s much smaller
intrinsic carrier concentration theoretically permits device operation at junction temperatures exceeding
800°C. 600°C SiC device operation has been experimentally demonstrated on a variety of
SiC devices.
The ability to place uncooled high-temperature semiconductor electronics directly into hot
environments would enable important benefits to automotive, aerospace, and deep-well drilling
industries. In the case of automotive and aerospace engines, improved electronic telemetry and
control from high-temperature engine regions are necessary to more precisely control the combustion
process to improve fuel efficiency while reducing polluting emissions. High-temperature capability
eliminates performance, reliability, and weight penalties associated with liquid cooling, fans, thermal
shielding, and longer wire runs needed to realize similar functionality in engines using conventional
silicon semiconductor electronics.