Modulating Fermi-level pinning and carrier injection efficiency in 2Dβ-TeO2/metal van der Waals heterostructure via interlayer distance.

Two-dimensional (2D) semiconductorβ-TeO2based field-effect transistors (FETs) have attracted considerable attention in the field of microelectronic devices owing to their high on/off ratio (>106), low subthreshold swing (<60 mV dec-1), and small effective hole mass (0.51 me). The contacts between theβ-TeO2semiconductor and metals are critical for enabling multifunctional device design. Here, we employed the first-principle calculation to investigate physical properties of contacts between 2D monolayerβ-TeO2and a series of metals T/H-XA2(X = V, Nb, Ta, and A = S, Se). The tunable sensitivity of the Schottky barrier to metal work function and the charge carrier injection efficiency with varying interlayer distance were systematically investigated. At the equilibrium interlayer distance, the contact approaches the ideal Schottky-Mott limit with Fermi-level pinning (FLP) factor |S|≈ 1. However, the tunneling probabilities for these contacts are low, varying from 0.12% for the contact with NbS2to 4.17% for the contact with VS2. Decreasing the interlayer distance to 2.0 Å leads to an increase in tunneling probability to 17.25% for the NbS2contact and 49.60% for the VSe2contact. However, the FLP factorSdecreases to 0.42 for electrons and 0.52 for holes, indicating enhanced FLP effects due to increased metal-induced gap states. Thus, optimizing the interlayer distance to balance carrier injection efficiency and Fermi-pinning effects is crucial for high-performance FETs. These findings provide a theoretical basis for the further design and fabrication of high-performance TeO2based transistors in the future.