A Single‐Crystalline High‐ κ K ₂ Mo ₃ O ₁₀ Dielectric for Two‐Dimensional Field‐Effect Transistors

Two‐dimensional (2D) semiconductors, such as MoS 2 , have been widely explored as channel materials for field‐effect transistors (FETs). However, the integration of 2D dielectric layers with high‐mobility semiconductors remains challenging, largely due to their relatively low dielectric constants and limited synthesis approaches. It is thus crucial to develop new 2D gate dielectrics that possess wider electronic bandgaps, higher dielectric constants, and better compatibility with 2D channel materials. Here, the K 2 Mo 3 O 10 single‐crystalline nanosheets are synthesized by chemical vapor deposition method, exhibiting a wide bandgap (∼4.09 eV) and high dielectric constant (∼39) for a 35‐nm‐thick sample, positioning it as a suitable candidate for dielectric layers. The MoS 2 FET with K 2 Mo 3 O 10 as the top‐gate dielectric exhibits a steep subthreshold swing (SS) as low as 76 mV dec −1 (with an average of approximately 140 mV dec −1 ) and an on/off current ratio of up to 10 7 (with an average of approximately 10 6 ). These results demonstrate the dielectric properties of K 2 Mo 3 O 10 , offering a viable option for gate dielectric development.