Intrinsic Electronic Properties of BN-Encapsulated, van der Waals Contacted MoSe₂ Field-Effect Transistors

Two-dimensional (2D) semiconductors have attracted considerable interest for their unique physical properties. Here, we report the intrinsic cryogenic electronic transport properties in few-layer MoSe₂ field-effect transistors (FETs) that are fully encapsulated in ultraclean hexagonal boron nitride dielectrics and are simultaneously van der Waals contacted with gold electrodes. The FETs exhibit electronically favorable channel/dielectric interfaces with low densities of interfacial traps (< 10¹⁰ cm⁻²), which lead to outstanding device characteristics at room temperature, including near-Boltzmann-limit subthreshold swings (65 mV/dec), high carrier mobilities (53–68 cm²⋅V⁻¹⋅s⁻¹), and negligible scanning hystereses (< 15 mV). The dependence of various contact-related parameters with temperature and carrier density is also systematically characterized to understand the van der Waals contacts between gold and MoSe₂. The results provide insightful information about the device physics in van der Waals contacted and encapsulated 2D FETs.