Improvement of Contact Resistance and 3D Integration of 2D Material Field‐Effect Transistors Using Semi‐Metallic PtSe2 Contacts

In this work, the potential of 2D semi‐metallic PtSe2 as source/drain (S/D) contacts for 2D material field‐effect‐transistors (FETs) through theoretical and experimental investigations, is explored. From the density functional theory (DFT) calculations, semi‐metallic PtSe2 can inject electrons and holes into MoS2 and WSe2, respectively, indicating the feasibility of PtSe2 contacts for both n‐ and p‐metal‐oxide‐semiconductor FETs (n‐/p‐MOSFETs). Indeed, experimentally fabricated flake‐level MoS2 n‐MOSFETs and WSe2 p‐MOSFETs exhibit a significant reduction in contact resistance with semi‐metallic PtSe2 contacts compared to conventional Ti/Au contacts. To demonstrate the applicability for large‐area electronics, MoS2 n‐MOSFETs are fabricated with semi‐metallic PtSe2 contacts using chemical vapor deposition‐grown MoS2 and PtSe2 films. These devices exhibit outstanding performance metrics, including high on‐state current (≈10−7 A/µm) and large on/off ratio (>107). Furthermore, by employing these high‐performance MoS2 n‐MOSFETs, vertically stacked n‐MOS inverters are successfully demonstrated, suggesting that 3D integration of 2D material FETs is possible using semi‐metallic PtSe2 contacts. In this work, the authors successfully demonstrate the effective reduction of contact resistance in MoS2 n‐and WSe2 p‐MOSFETs using semi‐metallic PtSe2 contacts. Furthermore, a vertically stacked n‐MOS inverter employing two MoS2 n‐MOSFETs with semi‐metallic PtSe2 contacts is realized in wafer‐scale, indicating the feasibility of 3D integration using semi‐metallic PtSe2.