Semiconductor-to-metal transition in platinum dichalcogenides induced by niobium dichalcogenides

Abstract

Metallizing 2D semiconductors is a crucial research area with significant applications, such as reducing the contact resistance at metal/2D semiconductor interfaces. This is a key challenge in the realization of next-generation low-power and high-performance devices. While various methods exist for metallizing Mo- and W-based 2D semiconductors like MoS2 and WSe2, effective approaches for Pt-based ones have been lacking. This study demonstrates that platinum dichalcogenides (PtX2, X = Se or Te) undergo a semiconductor-to-metal transition when grown on niobium dichalcogenides (NbX2, X = Se or Te). PtX2/NbX2 heterostructures were fabricated using molecular beam epitaxy (MBE) and characterized by Raman spectra, scanning transmission electron microscopy (STEM) and scanning tunneling microscopy/spectroscopy (STM/STS). Raman spectra and STEM confirm the growth of 1T-phase PtX2 and 1H-phase NbX2. Both 2D STS mapping and layer-dependent STS show that regardless of their layer numbers, both pristine semiconducting PtSe2 and PtTe2 are converted to metallic forms when interfacing with NbSe2 or NbTe2. Density functional theory (DFT) calculations suggest that the metallization of PtSe2 on NbX2 and PtTe2 on NbTe2 results from interfacial orbital hybridization, while for PtTe2 on NbSe2, it is due to the strong p-doping effect caused by interfacial charge transfer. Our work provides an effective method for metallizing PtX2 semiconductors, which may lead to significant applications such as reducing the contact resistance at metal electrode/2D semiconductor interfaces and developing devices like rectifiers, rectenna, and photodetectors based on 2D Schottky diodes. Graphical abstract: [Figure not available: see fulltext.]