Improved low-frequency noise in CVD bilayer MoS₂ field-effect transistors

In MoS₂ field-effect transistors, the current or voltage fluctuations related to either mobility- or number-dependent relationships are characterized by low-frequency noise. This noise can typically be used to evaluate the application limits of MoS₂-based electronic devices. In this work, the low-frequency noise characteristics of single-crystal bilayer MoS₂ grown by chemical vapor deposition (CVD) are systematically investigated and found to offer significant performance improvements compared with those based on the monolayer MoS₂ channel. At f = 100 Hz, the normalized drain current power spectral density (S_I/I_d²) is 2.4 × 10⁻¹⁰Hz⁻¹ and 3.1 × 10⁻⁹Hz⁻¹ for bilayer and monolayer MoS₂ transistors, respectively. The 1/f noise behavior can be accurately described by McWhorter's carrier number fluctuation model for both transistor types, suggesting that carrier trapping and de-trapping by dielectric defects is the dominant mechanism of 1/f noise in CVD MoS₂ transistors. Furthermore, a minimal WLS_I/I_d² of 3.1 × 10⁻¹⁰ μm²/Hz (where W is the gate width and L is the gate length) is achieved at V_bg = 3 V by effectively reducing the contact resistance of bilayer MoS₂ transistors using a back-gate voltage. These results demonstrate that CVD bilayer MoS₂ is a promising candidate for future large-scale 2D-semiconductor-based electronic applications with improved noise performance.