Abstract
Thin tellurium (Te) has been predicted as a potential two dimensional system exhibiting superior thermoelectric and electrical properties. Here, we report the synthesis of high quality ultrathin Te nanostructures and the study of their electrical properties at room temperature. High quality ultrathin Te nanostructures are obtained by high temperature vapor phase deposition on c-plane sapphire substrates. The obtained nanostructures are as thin as 3 nm and exhibit α-Te phase with trigonal crystal structure. Room temperature electrical measurements show significantly higher electrical conductivity compared to prior reports of Te in bulk form or in nanostructure form synthesized by low temperature vapor deposition or wet chemical methods. Additionally, these nanostructures exhibit high field effect hole mobility comparable to black-phosphorous measured previously under similar conditions.
Highlights
Tellurium (Te) is an elementary semiconductor predicted to exhibit striking physical properties in thin nanostructures such as extraordinarily high hole mobility, high thermoelectric performance, outstanding gate electrostatics, few interface traps, and dangling bond-free interfaces.1–4 Te exhibits a tunable bandgap as a function of thickness, from nearly direct 0.33 eV in the bulk to indirect 0.92 eV in monolayer.3,5 The trigonal crystal structure of Te consists of 1D helical chains of Te atoms stacked together on a 2D hexagonal lattice.6 The atomic distance between two neighboring Te atoms along the chain is 2.9 Å, whereas the atomic distance across the chains is 3.9 Å.7 Each Te atom is covalently bonded with its two nearest neighbors on the same chain, while the atoms on the nearest helical chains are weakly bonded and the weak bond is assumed to be van der Waals type8,9 or covalentlike quasibonding.4,6 Because of its unique crystal structure, nanostructures of Te can be synthesized as one-dimensional (1D) as well as two-dimensional (2D) nanostructures.1,3,10
Te nanostructures in 1D and 2D forms have been previously synthesized by solution-based methods, low temperature vapor phase deposition methods, and exfoliation of bulk Te
We observed high hole mobility which is comparable to the hole mobility of black phosphorous (BP) at room temperature
Summary
Tellurium (Te) is an elementary semiconductor predicted to exhibit striking physical properties in thin nanostructures such as extraordinarily high hole mobility, high thermoelectric performance, outstanding gate electrostatics, few interface traps, and dangling bond-free interfaces.1–4 Te exhibits a tunable bandgap as a function of thickness, from nearly direct 0.33 eV in the bulk to indirect 0.92 eV in monolayer.3,5 The trigonal crystal structure of Te consists of 1D helical chains of Te atoms stacked together on a 2D hexagonal lattice.6 The atomic distance between two neighboring Te atoms along the chain is 2.9 Å, whereas the atomic distance across the chains is 3.9 Å.7 Each Te atom is covalently bonded with its two nearest neighbors on the same chain, while the atoms on the nearest helical chains are weakly bonded and the weak bond is assumed to be van der Waals type8,9 or covalentlike quasibonding.4,6 Because of its unique crystal structure, nanostructures of Te can be synthesized as one-dimensional (1D) as well as two-dimensional (2D) nanostructures.1,3,10. We report high temperature synthesis of ultrathin Te nanostructures by vapor phase deposition. Using ZrTe2 as a source material and carefully controlling the substrate and source position to overcome the aforementioned challenge, we obtained high quality, ultrathin Te nanostructures that have thicknesses as low as scitation.org/journal/apm
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