A Universal van der Waals Tunneling Injector for Monolayer CMOS

ABSTRACT

Two‐dimensional (2D) semiconductors are poised to extend logic technology to the atomic‐thickness limit, yet monolayer complementary metal‐oxide‐semiconductor (CMOS) has been largely hampered by polarity‐dependent, thermionic‐emission‐dominated contacts that preclude a unified injection solution. Here, we introduce degenerately doped, crystalline SnSe ₂ as a universal source‐side van der Waals (vdW) injector capable of enforcing all‐tunneling carrier injection into both p ‐ and n ‐type monolayer channels. The combination of a large electron affinity (∼5.1 eV), degenerate carrier density (>10 ¹⁹ cm ⁻³ ), and atomically uniform vdW interfacial coupling enables polarity‐tailored tunneling mechanisms while effectively suppressing interfacial gap states. In p ‐type WSe ₂ , a type‐III (broken gap) alignment drives efficient band‐to‐band tunneling, yielding a >1000‐fold enhancement in drive current over conventional metal electrodes. In n ‐type MoS ₂ , the SnSe ₂ injector forms a type‐I heterojunction within the sub‐depletion‐width monolayer body, enabling a gate‐tunable injection that evolves from field‐controlled Fowler–Nordheim‐like tunneling to thickness‐limited tunneling, achieving an on/off ratio > 10 ⁹ and a subthreshold swing below 70 mV dec ⁻¹ . Integrating this single‐material injector, we demonstrate a monolayer CMOS inverter with a maximum voltage gain of ∼340 at V _DD = 2 V, establishing degenerate SnSe ₂ as a dual‐polarity vdW injector and providing a platform for high‐performance, low‐power 2D integrated circuits.