Bias Temperature Stress Instability of Multilayered MoS2 Field-Effect Transistors With CYTOP Passivation

Abstract

Bias temperature stress instability on multilayered MoS2 FETs was systematically investigated with the device scheme encapsulated with amorphous fluoropolymers [cyclized transparent optical polymer (CYTOP)] for the secure of minimization of external gas ambient effects. Large threshold voltage shifts ( $\Delta {V}_{\textsf {th}}$ ) for the negative bias temperature stress (NBTS) were observed, compared to the positive bias temperature stress (PBTS). Herein, the asymmetry behaviors on $\Delta {V}_{\textsf {th}}$ , observed in this paper, are ascribed to the sulfur vacancy in MoS2 layers, leading to large hole traps compared to electron traps in MoS2 layers. Moreover, high-temperature-sensitivity [ ${d}$ ( $\Delta {V}_{\textsf {th}}$ )/ dT ] on $\Delta {V}_{\textsf {th}}$ for PBTS than NBTS was observed, and their origins are possibly due to synergetic effects associated with large trap energy distribution ( ${k}_{o}{T}$ ) for electron trap levels.