2D Semiconductor Transistors using Layered van der Waals Oxide MoO₃ as High-<i>K</i> Gate Dielectric

The search for smaller field effect transistors is leading research towards atomically thin 2D semiconductor materials. Due to the decreasing size of these transistors, there must be an emphasis on finding compatible gate dielectrics that can be equally effective in the 2D regime. MoO₃ is an attractive multi-functional transition metal oxide replacement for gate dielectrics in field effect transistors due to its exfoliatable van der Waals structure in addition to its high dielectric constant. This study demonstrates that as-grown MoO₃ has a high dielectric constant, K, of approximately 35 at room temperature at low frequencies by fabricating parallel plate capacitors from these thin flakes. Mechanically exfoliated MoO₃ flakes are used to create 2D heterostructures with WSe₂, demonstrating that MoO₃ also induces holes in the WSe₂ layer. Most importantly, MoO₃ proves to be a strong gate dielectric when used as a top-gate material for WSe₂ heterostructure devices.