High Electron-Affinity Oxides Intercalation for p-Type Contacts in 2D Semiconductors.

Abstract

van der Waals stacking of 2D semimetals and semiconductors suppresses strong Fermi-level pinning, but weak interlayer coupling induces low carrier injection efficiency, limiting device performance. Conventional strategies (atomic/molecular intercalation, surface functionalization) suffer from uncontrollable intercalation and unstable functional groups that trigger performance degradation. Here, a universal, controllable, and stable doping strategy is used for p-type contacts in 2D semiconductors via in situ self-oxidation of 2D semimetals to form high electron-affinity transition-metal oxide intercalation (e.g., MoO₃ from 1T'-MoTe₂). These oxides with deep-lying electronic states and ultrahigh work functions act as strong electron acceptors, driving the transfer of electrons from MoS₂ toward the oxides, inducing p-doping in MoS₂ and reducing Schottky barriers for p-type ohmic contacts. Meanwhile, it enhances charge transfer and orbital hybridization to strengthen interfacial coupling. Asymmetric MoS₂ Schottky diodes fabricated with this strategy demonstrate excellent performance. This offers a simple, scalable contact engineering approach for high-performance 2D electronic devices.