5-3-1 High-Temperature Device Operation

5-3-1 High-Temperature Device Operation

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.

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