Open AccessControlling Injection Barriers for Ambipolar 2D Semiconductors via Quasi‐van der Waals Contacts
Author(s) -
Wang Junjun,
Wang Feng,
Wang Zhenxing,
Cheng Ruiqing,
Yin Lei,
Wen Yao,
Zhang Yu,
Li Ningning,
Zhan Xueying,
Xiao Xiangheng,
Feng Liping,
He Jun
Publication year - 2019
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201801841
Subject(s) - ambipolar diffusion , van der waals force , graphene , schottky barrier , thermionic emission , materials science , semiconductor , schottky diode , nanotechnology , condensed matter physics , fermi level , substrate (aquarium) , heterojunction , optoelectronics , diode , physics , electron , molecule , quantum mechanics , geology , oceanography
Barriers that charge carriers experience while injecting into channels play a crucial role on determining the device properties of van der Waals semiconductors (vdWS). Among various strategies to control these barriers, inserting a graphene layer underneath bulk metal may be a promising choice, which is still lacking experimental verification. Here, it is demonstrated that graphene/metal hybrid structures can form quasi‐van der Waals contacts (q‐vdWC) to ambipolar vdWS, combining the advantages of individual metal and graphene contacts together. A new analysis model is adopted to define the barriers and to extract the barrier heights in ambipolar vdWS. The devices with q‐vdWC show significantly reduced Schottky barrier heights and thermionic field emission activation energies, ability of screening the influence from substrate, and Fermi level unpinning effect. Furthermore, phototransistors with these special contacts exhibit enhanced performances. The proposed graphene/metal q‐vdWC may be an effective strategy to approach the Schottky–Mott limit for vdWS.