The researchers — who are based at the Institute of Metal Research in Shenyang China, the University of Science and Technology of China, Peking University and the Shenzhen Institute of Advanced Technology — fabricated micrometre-scale devices using a p-type germanium substrate as the current collector and two separate monolayer graphene emitter and base layers placed on top. Under bias, stimulated emission leads to an increase in the collector current and the transistors exhibited subthreshold swing values as low as 0.38 mV dec⁻¹ and on-currents of 165.2 μA μm⁻¹. Negative differential resistance behaviour with peak-to-valley current ratios of approximately 100 was possible at room temperature. This behaviour was also used to create multi-valued logic gates with reconfigurable logic.

Original reference: Nature 632, 782–787 (2024)