Si-Gate CMOS devices on a Si/CaF2/Si structure

Heteroepitaxial Si/CaF2/Si structure has been formed by molecular beam epitaxy(MBE), and Si-gate CMOS integrated circuits (100-stage inverter chains and 1/8 dynamic frequency dividers) have been successfully fabricated on the Si/CaF2/Si structure for the first time. For device fabrication, an improved CMOS process has been developed. Low temperature processes(maximum 950°C) have been chosen in order not to degrade the crystalline quality of the overgrown Si. The fabricated circuits have an inverter delay of 360 psec per stage at VDD5V, and the maximum divider frequency of 370 MHz at VDD7V.