Utilisation of janus material for controllable formation of graphene p–n junctions and superlattices

Abstract

Graphene-based device applications such as ultrafast transistors and photodetectors benefit from precise control over its carrier type and concentration as well as a combination of both high-quality p-and n-doped components with spatial control and seamless connection (p-n junctions/superlattices). However, this remains experimentally a challenge for an atom-scale control over the doping in graphene and the attendant formation of p-n junctions/superlattices. Here, we demonstrate that sandwiching a janus material (a functionalized graphene layer with one side by H atoms and another side by F atoms, defined as H-G-F) between MoSe 2 (BN) substrate and graphene allows us to effectively control the carrier type in graphene, where the janus material acts as an electron pump, facilitating the electron tunneling between MoSe 2 (BN) and graphene. Appropriate functionalization of the janus material would open the possibility of creating well ordered and atomically sharp graphene p-n junctions/superlattices in a single layer of graphene. Furthermore, upon applying an external electric field, the charge concentration in both n-type and p-type regions can be continuously tuned except for a platform area. A comprehensive and detailed picture built by density functional theory calculations sheds light on the physical mechanism of the observed doping course as well as its response to an external field. Our results not only introduce single-layer H-G-F as a new 2D Janus material with the ability of electron extraction, but also open up a new direction for local control over the properties of graphene without destroying its intrinsic structure.

Structural and electronic properties of Stanene-BeO heterobilayer

“…This difference in electric potential energies between the top and bottom Sn atoms results in the bandgap opening of stanene. This phenomenon of intrinsic dipole formation in the interface of heterolayer structure is common for other heterostructures with vdW interlayer interaction [45,52].…”

Tunable band gaps in silicene–MoS2heterobilayers

“…It turned out that for the heterostructures with vdW interlayer interactions, the thickness of the substrate hardly influenced the electronic states near E F . 46 Thus, in the following, we will focus on the case of the MoS 2 monolayer.…”

Selective Functionalization of Graphene Peripheries by using Bipolar Electrochemistry

“…Recently, there has been quite some interest in the synthesis of Janus graphene, where the top and bottom side of a graphene sheet has differing functionalities . Such structures show increased reactivity and high doping levels, enabling the realization of p–n junctions and are predicted to allow bandgap opening . In contrast to these works, we present here a straightforward approach to generate in‐plane bifunctional graphene, where two opposite peripheries of a graphene sheet are modified with two different metals.…”

“…[9c, 17b, 19] Recently,t here hasb een quite some interest in the synthesis of Janus graphene, where the top and bottom side of ag raphene sheet hasd iffering functionalities. [20] Such structures show increased reactivity and high doping levels, [20b] enabling the realizationo fp -n junctions [21] and are predicted to allow bandgap opening. [22] In contrast to these works, we present here as traightforward approach to generate in-plane bifunctional graphene, where two opposite peripheries of ag raphene sheet are modified with two different metals.T ypically, to obtain two different metals or functionalities on the same graphene sheet, or simply for edge selectivef unctionalization, some sort of local structuring or patterningi sn ecessary.…”