Ellipsometric characterization and density-functional theory analysis of anisotropic optical properties of single-crystal α-SnS

Abstract

We report on the anisotropic optical properties of single-crystal tin monosulfide (SnS). The components e a , e b , and e c of the pseudodielectric-function tensor hei ¼ he 1 i þ ihe 2 i spectra are taken from 0.73 to 6.45 eV by spectroscopic ellipsometry. The measured hei spectra are in a good agreement with the results of the calculated dielectric response from hybrid density functional theory. The hei spectra show the direct band-gap onset and a total of eight above-band-gap optical structures that are associated with the interband-transition critical points (CPs). We obtain accurate CP energies by fitting analytic CP expressions to second-energy-derivatives of the hei data. Their probable electronic origins and implications for photovoltaic applications are discussed. V C 2014 AIP Publishing LLC. [http://dx.

SnS thin films grown by sulfurization of evaporated Sn layers: Effect of sulfurization temperature and pressure

“…The straight line with an intercept on the hν axis determines direct E g between 1.16 and 1.22 eV. These values are in agreement with that of E g = 1.22 eV for SnS single crystal obtained by spectroscopic ellipsometry [18]. A satisfactory linear fit for indirect band gap estimation cannot be made for any sample by using n = ½ in the Eq.…”

Lattice dynamics of the tin sulphides SnS2, SnS and Sn2S3: vibrational spectra and thermal transport

“…This anisotropy in thermal-transport properties mirrors that in its electrical properties. 68 The weak interlayer interactions along the c axis of SnS 2 lead to poor thermal transport in that direction compared to the in-plane conductivity. By analogy, the very low κ latt of Sn 2 S 3 compared to SnS could be ascribed to its reduced dimensionality, and indeed the thermal conductivity is an order of magnitude larger along the crystallographic b axis, corresponding to the direction of the bonding along the chains; however, at 0.14 W m –1 K –1 at 300 K, this is still close to an order of magnitude smaller than the conductivity along the “easy” direction in SnS at the same temperature (1.10 W m –1 K –1 ), implying that intrinsic anharmonicity, as well as low dimensionality, is responsible for its poor thermal transport.…”

Facile Formation of Nanodisk‐Shaped Orthorhombic SnS Layers from SnS2 Particles for Photoelectrocatalytic Hydrogen Production

“…[2][3][4][5][6] Recently,s cattered layerso fS nS on either mica or Si wafer, prepared fromc ommercialS nS powers via av apor phase transportm ethod, have been successfully used in variousa pplications such as the field effect transistors, [14,15] anisotropic field-effect transistors, [5] solid-ionb atteries (chemically derived SnS), [16] near-infraredp hotodetectors, [17] gas dependentp hotodetectors, [18] and anisotropic core-shell photoactive heterostructures. [19] Such diverse applicationso fS nS layers reflect the inherentf unctional richness of the SnS layers such as 2D anisotropic optical, electrical and thermoelectric properties of SnS [5,6,10,20] as has been experimentally determinedf rom the thickness, angle, and temperature-dependent Raman characteristics. [5,21] Various functional devices employing 2D SnS materials have been prepared using chemical routes [10,[22][23][24][25][26][27][28] as well as vacuum routes.…”