AVS 65th International Symposium & Exhibition
    2D Materials Focus Topic Tuesday Sessions
       Session 2D+EM+MI+MN+NS-TuA

Paper 2D+EM+MI+MN+NS-TuA2
Two-dimensional Field-effect Light Emitting Transistors

Tuesday, October 23, 2018, 2:40 pm, Room 201B

Session: 2D Device Physics and Applications
Presenter: Junyoung Kwon, Yonsei University, Republic of Korea
Authors: J. Kwon, Yonsei University, Republic of Korea
H. Ryu, Yonsei University, Republic of Korea
J.Y. Lee, Korea University, Republic of Korea
C.H. Lee, Korea University, Republic of Korea
G.H. Lee, Yonsei University, Republic of Korea
Correspondent: Click to Email
Two dimensional (2D) materials and their heterostructures hold great promises in various applications due to their unique properties and newly discovered physics. Especially, high exciton binding energy and emergence of charged excitons, i.e. trions, have shown that 2D semiconductors, such as transition metal dichalcogenides (TMDs), are promising candidates for new concept optoelectronics. Although lots of optoelectronic devices based on the van der Waals heterostructures of 2D materials, such as photodetectors, solar cells, and light emitting devices, have been demonstrated, development of novel optoelectronic devices is still required to fully utilize unique properties of 2D materials and enable multi-functions and versatile applications. Here we demonstrate 2D filed-effect light emitting transistors (2D-FELET) consisting of monolayer WSe2 (light-emitting channel layer) and graphene contacts (tunable carrier injection electrodes). We encapsulated monolayer WSe2 with two pieces of hexagonal boron nitride and fabricated graphene contacts to two ends of WSe2. To selectively inject different types of charge (electrons and holes) at two graphene contacts, two separate top gates on top of WSe2-graphene overlap regions were fabricated. By independent modulation of two top gates, Schottky barrier heights for electrons and holes can be tuned, which enables the selective charge injections. When two top gates are oppositely biased, electrons can be injected from one end of WSe2 channel and holes can be injected from the other end. These opposite charges are recombined at the middle of WSe2 channel, leading to strong light emission. The performance of the 2D-FELETs is tunable by additional electrical field from back gate. Furthermore, the devices produced in this work can be used as polarity-tunable FETs and photodetectors, simultaneously, which are beneficial for further CMOS integration. Our study shows great potential of 2D-FELETs toward future optoelectronic applications, which request ultra-thinness, transparency, flexibility, high efficiency, multi-functions, and high integration.