A full adder using resonant-tunneling hot electron transistors (RHETs)

Full adders are demonstrated using InGaAs-In(AlGa)As RHETs. The RHET's emitter and base electrodes were self-aligned using a SiO/sub 2/ sidewall and angled beam ion milling. The common-base current gain was about 0.9 and the emitter current peak-to-valley ratio was 10. The RHET full adder was constructed using a three-input exclusive-OR logic gate and a three-input majority logic gate. The authors confirmed normal operation of the full adder at 77 K. Only seven RHETs were needed for the full adder, about one-quarter of bipolar transistors that would have been required.>