Functional devices based on real space transfer in Si/SiGe structure

A charge injection transistor, which operates as an exclusive-OR logic gate, and a monolithic multiterminal device, electrically reprogrammable between OR and NAND logic function, have been successfully implemented in a Si-Si/sub 0.7/Ge/sub 0.3/ heterostructure grown by rapid thermal epitaxy on a Si substrate. Room temperature operation of the charge injection transistor is demonstrated, with 10 dB on/off ratio for the exclusive-OR logic function. Microwave measurements indicate a short circuit current gain cutoff of 6 GHz, for a device with a source-drain distance of 0.5 /spl mu/m. Device simulations were used to identify primary dependencies of the device performance on the parameters used in the design of the structure. Further structural improvements are suggested.