Nanostructured Bi Grown on Epitaxial Graphene/SiC

Abstract

Controllable growth of metal nanostructures on epitaxial graphene (EG) is particularly interesting and important for the applications in electric devices. Bi nanostructures on EG/SiC are fabricated through thermal decomposition of SiC and subsequent low-flux evaporation of Bi. The orientation, atomic structure, and thickness-dependent electronic states of Bi are investigated by scanning tunneling microscopy/spectroscopy. It is found that metallic Bi nanoflakes and nanorods prefer to grow on the SiC buffer layer region with higher diffusion barrier, but Bi nanoribbons are formed on regularly ordered EG. Although the thicker Bi nanoribbons of 11 monolayers on EG are still metallic, the thinner ones become semiconducting owing to the interfacial effect. This indicates that the electronic states and physical properties of Bi are substrate-dependent. The results are helpful for the design of Bi- and graphene-based electronic and spintronic devices.

Epitaxial Growth and Structural Properties of Bi(110) Thin Films on TiSe2 Substrates

“…Indeed, Schindler and co-workers recently reported the observation of topologically protected hinge states in Bi(111) nanostructures and proposed that they are high-order TIs . When other substrates such as Si(111), Ge(111), W(110), graphene, , graphite, , and NbSe 2 were adopted, (110)-oriented thin films were formed prior to the (111)-oriented ones at the initial stage because Bi(110) thin films with a black phosphorus (BP) structure are energetically more favorable than Bi(111) . However, the effect of the substrates on the growth and structure of the Bi(110) thin films have rarely been addressed.…”

Epitaxial Growth of Free-Standing Bismuth Film on Graphene Embedded with Nontrivial Properties

“…Consequently, it is evident that Bi(111) bilayers have been constructed on top of the graphene substrate at the coverage of around 7 bilayers. Electronic properties of Bi(110) layers on graphene have been investigated by DFT and scanning tunneling spectroscopy (STS) in the literature, 33,35,41 which is not the focus of the present study. Meanwhile, the atomic buckling and the mixture of nanoribbons, nanorods, and nanoflakes make the ARPES measurement rather difficult.…”

“…Graphene, due to its chemical inertness as well as its atomic smoothness, is therefore an ideal template for the growth of free-standing clusters and nanostructures. In fact, graphite was utilized already to guide the growth of thin bismuth films, while no obvious interfacial hybridization has been discovered. − Consequently, the graphene substrate is chosen herein, aiming to the growth of expected free-standing bismuth layers to exploit its intrinsic electronic properties excluding substrate influences. More interestingly, a high spin transporting property has also been demonstrated for the graphene/SiC complex with the spin diffusion length exceeding 100 μm, while nontrivial Bi BLs are perceived with strong spin-momentum locking. − Consequently, the combination of bismuth film and graphene might also be an ideal platform for spin injection and transportation manipulation, thus providing a new paradigm for spin information processing toward postsemiconductor electronics.…”

Achieving a Large Energy Gap in Bi(110) Atomically Thin Films

“…[1][2][3][4][5] Being a heavy element with unique and anomalous electronic properties, the semimetal bismuth (Bi) is one of the most extensively studied materials and has played an exceptional role in revealing many interesting phenomena in solid-state physics. [6][7][8][9][10][11][12] In particular, ultrathin Bi films have provided a representative platform for fundamental and technological explorations through delicate tailoring of their atomic and electronic structures, [13][14][15][16][17][18][19][20][21] interfacial structure, [2,3,[22][23][24][25] charge doping, [21,26] etc. When Bi is deposited on alternative substrates with a few-layer atomic thickness, such as Si(111), [27] highly oriented pyrolytic graphite (HOPG), [13,22,28] epitaxial graphene, [23,29] NbSe 2 , [21,26] and ferromagnetic Fe 3 GeTe 2 , [25] Bi normally forms Bi(110)-oriented thin films.…”