“…186,187 and Darwish et al 188 that the subthreshold drain current characteristics of MOS-SOS devices differed from their bulk counterpart. Darwish et al 188 measured the subthreshold characteristics of MOS-SOS devices and verified that they are independent of thickness when X s is greater than X d . If the depletion region does reach the silicon-sapphire interface, however, the characteristics will be degraded due to the interface states.…”