Epitaxial Growth and Band Structure of Te Film on Graphene

Abstract

Tellurium (Te) films with monolayer and few-layer thickness are obtained by molecular beam epitaxy on a graphene/6H-SiC(0001) substrate and investigated by in situ scanning tunneling microscopy and spectroscopy (STM/STS). We reveal that the Te films are composed of parallel-arranged helical Te chains flat-lying on the graphene surface, exposing the (1 × 1) facet of (101̅0) of the bulk crystal. The band gap of Te films increases monotonically with decreasing thickness, reaching the near-infrared band for the monolayer Te. An explicit band bending at the edge between the monolayer Te and graphene substrate is visualized. With the thickness controlled in the atomic scale, Te films show potential applications of electronics and optoelectronics.

Tellurium: Fast Electrical and Atomic Transport along the Weak Interaction Direction

“…Two-dimensional (2D) materials, such as graphene, MoS 2 , black phosphorus and hexagonal boron nitride, show great promise for many applications, including electronics, optoelectronics, energy conversion, and energy storage 1 . Recently, few-layer Te joins the family of 2D materials [2][3][4][5][6][7] . It exhibits air-stable transistor performance comparable or superior to other 2D materials 7 , making Te attractive for nanoelectronics.…”

Emerging Applications of Elemental 2D Materials

“…For group VI elements, synthesis efforts have focused on 2D analogs of selenium (Se) and tellurium (Te) . Tellurene thin films with a thickness, t , ≈10 nm were grown by high‐vacuum thermal evaporation dating back in the 1970s while selenium monolayers were electrochemically deposited on Au (111) in 1997 .…”

“…However, prior to the discovery of exciting 2D physics, the stability and properties of 2D and ultrathin ( t < 10 nm) allotropes were not deeply explored nor their structures heavily pursued. Recently, Zhu et al and Chen et al have demonstrated the growth of β‐type tellurene on highly oriented pyrolytic graphite (HOPG) substrates while Huang et al demonstrated monolayers of tellurene with the <0001> helical chains oriented in the substrate plane on graphene/6H‐SiC(0001) substrates grown by MBE . Wang et al showed solution‐phase growth of free‐standing micron scale tellurene single crystals tens of nm thick, which could undergo a postthinning process to near monolayer (≈0.5 nm) thickness .…”

“…For group VI elements, synthesis efforts have focused on 2D analogs of selenium (Se) and tellurium (Te). [27,28,55,91,92] Tellurene thin films with a thickness, t, ≈10 nm were grown by high-vacuum thermal evaporation dating back in the 1970s [93] while selenium monolayers were electrochemically deposited on Au (111) in 1997. [94] However, prior to the discovery of exciting 2D physics, the stability and properties of 2D and ultrathin (t < 10 nm) allotropes were not deeply explored nor their structures heavily pursued.…”

“…Recently, Zhu et al and Chen et al have demonstrated the growth of β-type tellurene on highly oriented pyrolytic graphite (HOPG) substrates while Huang et al demonstrated monolayers of tellurene with the <0001> helical chains oriented in the substrate plane on graphene/6H-SiC(0001) substrates grown by MBE. [27,91,92] Wang et al showed solution-phase growth of free-standing micron scale tellurene single crystals tens of nm thick, which could undergo a postthinning process to near monolayer (≈0.5 nm) thickness. [91] Qin et al demonstrated vapor phase deposition of selenene flakes, t = 5-15 nm and lateral dimensions ≈10 µm, in a tube furnace at ≈200 °C under flowing Ar.…”