Crystal structure and band-edge transitions of ReS2−xSex layered compounds

Growth and characterization of tungsten and molybdenum-doped ReSe2 single crystals

“…It is a subject of considerable interest because of its extremely anisotropic electrical, optical and mechanical properties [3], as a promising solar-cell material in electrochemical cells [4,5]. Owing to the potential technological applications of the material, a variety of efforts have been devoted to the theoretical and experimental understanding of the solid-state properties of ReSe 2 [6][7][8]. It is known that doping of semiconductor material leads to a change in not only electrical but also optical properties.…”

“…The temperature dependent electrical conductivity measurements along and perpendicular to the b-axis in the van der Waals plane were carried out in the temperature range from 130 to 300 K. The indirect band edge transitions and direct band-edge excitonic transitions were studied by polarization-dependent transmittance and piezoreflectance (PzR), respectively. For comparison purpose, similar measurements for the undoped ReSe 2 single crystals were also included [6][7][8]. The effects of the dopants W and Mo on the electrical transport and optical properties were analyzed and discussed.…”

Identifying light impurities in transition metal dichalcogenides: the local vibrational modes of S and O in ReSe2 and MoSe2

“…In each case, one S atom was introduced, with separate calculations being made for each of the four non-equivalent chalcogen positions. This gave effective concentrations of twice, equal to, and half of the experimental concentration of S. Initial unit cell parameters and atomic coordinates were taken from Lamfers et al 23 or Ho et al 32 with similar results; these were relaxed to obtain atomic forces less than 10 −3 eV/Å. Similar criteria gave good agreement for the phonons of other TMDs.…”

“…The inter-layer coupling is unusually weak compared to other TMDs, [24][25][26] though recent angle-resolved photoemission spectroscopy (ARPES) studies show that the band structure of the bulk ReX 2 family still has a three-dimensional character. [27][28][29][30] ReSe 2 is an indirect band gap semiconductor for all numbers of layers [31][32][33][34] with a band gap of 1.36 eV 34 whilst there is disagreement as to the nature of the band gap for bulk ReS 2 , with some groups reporting an indirect band gap of 1.41 eV and others claiming a direct band gap of 1.5 eV. [31][32][33][34][35][36] In this paper, we focus on the alloys of composition ReSe 2 -x S x .…”

“…These alloys are of interest for two major reasons. Firstly, by changing the composition of sulfur within these alloys it is possible to tune the band gap, 32,37 as found for other TMD alloys 38 and alloys can be produced over the whole composition range, with the anisotropic trigonal structure being preserved throughout. Secondly, the more well-known TMDs exhibit strong spinorbit splittings (SOS) in the valence band, with the magnitude of this SOS being 180 meV at the K and K' points of the Brillouin zone for bulk MoS 2 .…”