Two-dimensional vertical p-n diodes with sub-2-nm channel lengths

Ultra-scaled p-n diodes are essential to the development of complementary metal oxide semiconductor (CMOS) integrated circuits. However, realizing p-n diodes with sub-5-nm channel length still faces great challenge due to the interface defects and short channel effect. Here, we demonstrate 1.9-nm WSe2/WS2 vertical p-n diodes, realizing a high on/off ratio of similar to 8 x 10(3) and a rectification ratio of similar to 17. Furthermore, the device with 4.7-nm channel length exhibits an excellent on/off ratio of similar to 10(4) and a rectification ratio of similar to 10(3). The high performances stem from the near-ideal band-alignment via designed Schottky-barrier-free contact, and the minimized tunneling current and Fermi-level pinning via full van der Waals (vdW) interfaces without defects. Thus, the intrinsic characteristics of p-n diodes are realized. This strategy can also be extended to other p-n junctions such as WSe2/MoSe2 and WSe2/MoS2, indicating universality of our strategy. Our devices provide great insight into ultimate scaling of electronic devices toward further development of integrated circuits.