High Temperature Electronics Using Complementary Heterostructure FET (CHFET) Technology

The characteristics of Complementary Heterostructure FET (CHFET) devices and logic circuits to 500 °C are reponed. Several features of the CHFET's Al0.75GaAs/In0.25GaAs/GaAs heterostructure were found to improve PET operation at high temperatures. The n-channel CHFET maintained an extrinsic transconductance Gmin excess of 100 mS/mm at 500 °C and gate leakage was 5-10x lower than for bulk GaAs MESFETs. The CHFET heterostructure also provides a complementary p-channel PET which was temperature-tested. Buffered CHFET ring oscillators maintained propagation delays of 320 pS/gate at 400 °C with no degradation after 50 hours. Suggestions are offered to reduce sub-threshold leakage which limited the performance of devices in thisstudy.