Electrical Contacts in Monolayer Blue Phosphorene Devices

Semiconducting monolayer (ML) blue phosphorene (BlueP) shares similar stability with ML black phosphorene (BP) and has recently been grown on the Au surface. Potential ML BlueP devices often need a direct contact with metal to inject carrier. Using ab initio electronic structure calculations and quantum transport simulations, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor (FET) configuration for the first time.There is a strong Fermi level pinning (FLP) in the ML BlueP FETs due to the metal induced gap states (MIGS). The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides an insight into the ML BlueP-metal interfaces but also helps to design the ML BlueP device.