Patternable laser-oxidized Ta2O5 dielectric and TaS2 contact for optimizing subthreshold swing of MoS2 field-effect transistors

Recent progress has achieved a high on-current density and a low contact resistivity for n -type field-effect transistors using two-dimensional (2D) semiconductors such as MoS 2 and WSe 2 . However, other issues with device parameters remain unresolved, such as the use of complementary transistors with a single 2D semiconductor, environmental packaging, and dielectric layers. Integrating an optimal dielectric and ideal interfacial contact for mass production will play a crucial role in future electronics designs. Here, we demonstrate patternable laser oxidation to convert TaS 2 into Ta 2 O 5 as an ultra-flat dielectric layer, having been evidenced by energy-dispersive X-ray spectroscopy, nano-X-ray absorption near-edge structure, and atomic force microscopy. With this patternable conversion, we also demonstrate the implementation of TaS 2 as contact electrodes on the MoS 2 channel material. The Ta 2 O 5 layer reveals a dielectric constant of ∼15.98 and a breakdown field of ∼5.5 MV/cm. A high on-current density of ∼34.7 μ A / μ m is achievable in Bi-contacted devices at a channel length of 1.0 μm. Moreover, the TaS 2 -contacted MoS 2 transistors on Ta 2 O 5 present an extremely low subthreshold swing of ∼59.8 mV/dec and a minimal hysteresis of ∼0.15 V. This indicates the superior feature of the Ta 2 O 5 dielectric through patternable laser oxidation while keeping an ultra-flat interfacial surface.