Theoretical study on high-frequency graphene-nanoribbon heterojunction backward diode

We propose and analyze a heterojunction backward diode for millimeter- or terahertz-wave detection using edge-modified graphene nanoribbons (GNRs). According to the electron-affinity difference between a hydrogen-terminated GNR and a fluorine-terminated GNR, it is possible to construct a staggered-type lateral heterojunction diode. First-principles calculations reveal that because of band-to-band tunneling, the diode has a nonlinear current of the order of kA/m. The small junction area contributes to the reduction of the intrinsic junction capacitance. Equivalent-circuit analyses show that when the total capacitance is reduced below 100 aF, the diode exhibits a voltage sensitivity of 3.79 × 103 V/W at 300 GHz.