Enhancing the Performance of MoS2 Field-Effect Transistors Using Self-Assembled Monolayers: A Promising Strategy to Alleviate Dielectric Layer Scattering and Improve Device Performance

Field-effect transistors (FETs) based on two-dimensional molybdenum disulfide (2D-MoS₂) have great potential in electronic and optoelectronic applications, but the performances of these devices still face challenges such as scattering at the contact interface, which results in reduced mobility. In this work, we fabricated high-performance MoS₂-FETs by inserting self-assembling monolayers (SAMs) between MoS₂ and a SiO₂ dielectric layer. The interface properties of MoS₂/SiO₂ were studied after the inductions of three different SAM structures including (perfluorophenyl)methyl phosphonic acid (PFPA), (4-aminobutyl) phosphonic acid (ABPA), and octadecylphosphonic acid (ODPA). The SiO₂/ABPA/MoS₂-FET exhibited significantly improved performances with the highest mobility of 528.7 cm² V^-1 s^-1, which is 7.5 times that of SiO₂/MoS₂-FET, and an on/off ratio of ~10⁶. Additionally, we investigated the effects of SAM molecular dipole vectors on device performances using density functional theory (DFT). Moreover, the first-principle calculations showed that ABPA SAMs reduced the frequencies of acoustic and optical phonons in the SiO₂ dielectric layer, thereby suppressing the phonon scattering to the MoS₂ channel and further improving the device's performance. This work provided a strategy for high-performance MoS₂-FET fabrication by improving interface properties.