Van der Waals metal-semiconductor junction: weak Fermi level pinning enables effective tuning of Schottky barrier

摘要

Two-dimensional (2D) semiconductors have shown great promise in(opto)electronic applications. However, their developments are limited by alarge Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which isdifficult to tune by using conventional metals due to the strong Fermi levelpinning (FLP) effect. Here we show that, this problem can be overcome by using2D metals, which are bounded with 2D semiconductors through van der Waals (vdW)interaction. This success relies on a weak FLP at the vdW MSJ, which isattributed to the suppression of metal-induced gap states. Consequently, the SBbecomes tunable and can vanish with proper 2D metals (e.g. H-NbS2). This worknot only offers new insights into the fundamental properties ofheterojunctions, but also uncovers great potential of 2D metals in deviceapplications.