The non-volatile electrostatic doping effect in MoTe2 field-effect transistors controlled by hexagonal boron nitride and a metal gate
Muhammad Asghar Khan, Muhammad Farooq Khan, Shania Rehman, Harshada Patil, Ghulam Dastgeer, Byung Min Ko, Jonghwa Eom
Abstract
Abstract The electrical and optical properties of transition metal dichalcogenides (TMDs) can be effectively modulated by tuning their Fermi levels. To develop a carrier-selectable optoelectronic device, we investigated intrinsically p-type MoTe 2 , which can be changed to n-type by charging a hexagonal boron nitride (h-BN) substrate through the application of a writing voltage using a metal gate under deep ultraviolet light. The n-type part of MoTe 2 can be obtained locally using the metal gate pattern, whereas the other parts remain p-type. Furthermore, we can control the transition rate to n-type by applying a different writing voltage (i.e., − 2 to − 10 V), where the n-type characteristics become saturated beyond a certain writing voltage. Thus, MoTe 2 was electrostatically doped by a charged h-BN substrate, and it was found that a thicker h-BN substrate was more efficiently photocharged than a thinner one. We also fabricated a p–n diode using a 0.8 nm-thick MoTe 2 flake on a 167 nm-thick h-BN substrate, which showed a high rectification ratio of ~ 10 −4 . Our observations pave the way for expanding the application of TMD-based FETs to diode rectification devices, along with optoelectronic applications.