Ultrathin β-tellurium layers grown on highly oriented pyrolytic graphite by molecular-beam epitaxy

Abstract

Monolayer tellurium (Te) or tellurene has been suggested by a recent theory as a new two-dimensional (2D) system with great electronic and optoelectronic promises. Here we present an experimental study of epitaxial Te deposited on highly oriented pyrolytic graphite (HOPG) by molecular-beam epitaxy. Scanning tunneling microscopy of ultrathin layers of Te reveals rectangular surface cells with the cell size consistent with the theoretically predicted β-tellurene, whereas for thicker films, the cell size is more consistent with that of the [101[combining macron]0] surface of the bulk Te crystal. Scanning tunneling spectroscopy measurements show that the films are semiconductors with the energy band gaps decreasing with increasing film thickness, and the gap narrowing occurs predominantly at the valence-band maximum (VBM). The latter is understood by strong coupling of states at the VBM but a weak coupling at conduction band minimum (CBM) as revealed by density functional theory calculations.

Few-layer Tellurium: one-dimensional-like layered elementary semiconductor with striking physical properties

“…In addition, the nearly isotropic in-plane optical absorbance yields stronger absorption than that of those nanowires or nanoplates in the α'-phase, which was a result of the inter-chain (intralayer) CLQB as extended from previously found interlayer cases of other 2D layers. The highest mobility was found in the CLQB dominant direction; this is largely out of our exception and Note added: During the preparation for this manuscript, we became aware that few-layer α-Te samples have been synthesized in large scale and fabricated into electronic devices [58] and the synthesis of it was also realized by molecular beam epitaxy [63,64], as well as the βand γphases were theoretically discussed [65]. Including Fig.…”

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

“…Therefore, it has been assumed that the interaction along the chain is strong and covalent, while between the chains is weak. Some papers claim that the inter-chain interaction is van der Waals (vdW) type 5,8,[11][12][13][14][15][16][17] . In anisotropic materials, the transport along weak interaction direction is usually much slower than that along chemical bond directions.…”

Atomic force microscopy studies on sulfur-, selenium- and tellurium-based metal chalcogenide thin films: A review

“…Tellurium films show p-type conduction (Begona et al, 2015), because of lattice defects acting as acceptors. The band gap about 0.34 eV (Chen et al, 2017) and the carrier concentration at room temperature is in the range of (1-5) × 10 18 cm -3…”