Improved integration of ultra-thin high-k dielectrics in few-layer MoS_2 FET by remote forming gas plasma pretreatment

摘要

The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS_2 transistor with ultra-thin A1_2O_3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS_2 surface. The top gate MoS_2 FET exhibited excellent electrical performance, including high on/off current ratio over 10~9, subthreshold swing of 85 mV/ decade and field-effect mobility of 45.03 cm_2/V s. Top gate leakage current less than 0.08 pA/μm~2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS_2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.