The direct-current and alternating-current transport properties of bilayer α- and α†-borophenes

Abstract

By combining density functional theory with the non-equilibrium Green's function method, in the present study we investigated the direct-current (DC) and alternating-current (AC) transport properties of bilayer (BL) α- and α^†-borophenes. We found that BL α-borophene has rich DC transport properties such as the steady current (SC), constant conductance (CC) and negative differential resistance (NDR) effects. In the same DC bias voltage range, the SC-to-CC and SC-to-NDR transitions can be realized by changing the stacking pattern. As for BL α^†-borophene, the stacking pattern can significantly influence the threshold bias voltage. Furthermore, our results indicate that BL α- and α^†-borophenes have different AC transport behaviors. In the low-frequency range, the former exhibits inductive characteristics, while the latter is capacitive; the corresponding equivalent AC circuits are also suggested. In addition, the inductive-to-capacitive and capacitive-to-inductive transitions were observed in these BL structures by adjusting the interlayer distances. In particular, as the interlayer distances gradually increase, the red shift and blue shift phenomena are found for the first critical points of BL α- and α^†-borophenes respectively. We hope that the present study could provide more insights into the DC and AC transport properties of BL α- and α^†-borophenes.