Suppression of channel migration in 2D multilayer ReS₂ via hBN passivation

Multilayer rhenium disulfide (ReS₂) has garnered attention due to the decoupled van der Waals interactions between its adjacent layers, resulting in significantly higher interlayer resistivity compared to other layered materials. However, for field-effect transistors (FETs) using two-dimensional (2D) materials, air exposure can degrade the sensitivity. Additionally, due to the decoupling layer, conduction layer migration under drain voltage (V_DS) changes affects electrical properties. This paper investigates the electrical characteristics of multilayer ReS₂ FETs after surface hexagonal boron nitride (hBN) passivation. Electrical characteristics for channel lengths of 0.30 μm, 1.3 μm, and 3.5 μm were compared to analyze the effects of surface hBN passivation. Passivation was implemented using a standard transfer technique. After hBN passivation, threshold voltage (V_th) increased and subthreshold swing improved. Additionally, it was observed that when the channel length is short, the variation in electrical properties in response to changes in V_DS decreases. In the low-frequency noise analysis, a 1/f² spectrum was observed at 0.30 μm and 1.3 μm before hBN passivation, but this spectrum disappeared after passivation. This indicates that the migration of the conduction layer, which occurs due to V_DS in short channels, is suppressed after hBN passivation. This study holds significance in understanding the change of electrical characteristics and the movement of conduction channel in 2D materials based on surface properties.