Optical absorption band edge in single-crystal GeS

Wiley, J. D.; Breitschwerdt, A.; Schönherr, E.

doi:10.1016/0038-1098(75)90311-7

Cited by 67 publications

(40 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This loss of luminescence may be one reason that decreasing thickness results in reduction of PL intensity of the GeS multilayer. [12] When T > 77 K, the FX is ionized and the band-to-band emission BE will eventually dominate the main photoluminescence intensity up to 300 K. Besides, as shown in Figure 3a, the signal due to DAP is stronger than that of the FX emission; this indicates strong imperfection (impurity and defect levels) localization effect at low temperature. Greater stacking of the GeS layer (A part) will enhance the [100] polarized emission intensity of the up-and-down GeS bonds in the armchair chains.…”

Section: Doi: 101002/adom201600814mentioning

confidence: 94%

“…[10,11] Layered GeS has received more attention than its monolayer equivalent because of its suitable band-gap (ca. 1.5-1.7 eV) [12,13] and high absorption coefficient for solar-cell fabrication, excellent cycling performance for reversible lithium batteries, [14] anisotropic optical property, [15] as well as for being considered a "green" material and sustainable. Previous research focused mostly on bulk GeS and seldom on the nanoscale.…”

Section: Doi: 101002/adom201600814mentioning

confidence: 99%

See 1 more Smart Citation

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

2016

Advanced Optical Materials

View full text Add to dashboard Cite

1 of 6) 1600814and optical absorption behaviors of GeS nanosheets have been studied and proposed for energy applications, [16,17] however, the light-emitting property of a thin multilayer GeS was not yet explored.Herein, in-plane optical anisotropy of band-edge emission of a multilayer GeS stripe (t ≈ 40 nm) is characterized by using polarized micro-photoluminescence (µPL) measurement with polarization angles ranging from 0 to 90° with respect to the multilayer's longest crystal edge (b axis). Light emission from multilayer GeS is completely forbidden at θ = 0° (E||b), and fully allowed (intense light) at θ = 90° (E||a), which obeys a dichroic Malus law [18] for the emission peak at 1.622 eV. Multilayer GeS behaves like a dichroic light emitter with linear polarization along the multilayer's a axis. To understand the band-edge characteristic of the GeS multilayer, polarized thermoreflectance (PTR) measurement by using microscope white-light guiding was also implemented. The selection rule of the PTR spectra also reveals that the lower band-edge transition E A = 1.622 eV is only allowed with E||a polarization while another higher energy transition, E B = 1.732 eV, appears merely along the E||b polarization in the multilayer. In-plane anisotropy of the c plane GeS multilayer occurs with linear polarization along a and b axes. The energy position of the E A transition matches well with the main band-edge emission observed by µPL, while the E B transition may probably originate from valence-band splitting (dominated by the S p orbital) of the multilayer GeS. The structural and optical anisotropy of the multilayer GeS is discussed here.Layered single crystals of IV-VI GeS with different areas, sizes, and thicknesses were grown by using the chemical vapor transport (CVT) method [19] with iodine as the transport agent. The crystals were prepared from their elements (Ge: 99.999% pure and S: 99.999%) by reaction at 600 °C for two days in evacuated quartz ampoules. Sulfur was added in 1 mol% excess with respect to the stoichiometric mixture of the constituent elements. About 10 g of the elements, together with an appropriate amount of transport agent (I 2 about 10 mg cm −3 ), were introduced into a quartz ampoule (22 mm OD, 17 mm ID, 20 cm length), which was then cooled with liquid nitrogen, evacuated to 10 −6 Torr and sealed. The mixture was slowly heated to 600 °C and maintained at this temperature for two days. The temperature was then altered from 600 °C (heating zone) → 520 °C (growth zone) with a gradient of -4 °C cm −1 for crystal growth. The reaction was left 240 h to produce large single crystals. The as-grown GeS crystals are dark red and have a shiny surface with an area of up to 5 mm 2 and thickness of up to 100 µm. The crystals are mostly like ribbon or stripe-shape layered crystals (see Figure S1 in the Supporting Information). The powder and single-crystal X-ray diffraction (XRD) results of GeS shown in Figure S1 reveal an orthorhombic phase. The lattice constants are a = 4.36 Å, b = 3.67 Å, and c = 10.53 Å,

show abstract

Section: Doi: 101002/adom201600814mentioning

confidence: 94%

Section: Doi: 101002/adom201600814mentioning

confidence: 99%

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

2016

Advanced Optical Materials

View full text Add to dashboard Cite

show abstract

“…Theory (DFT-LDA) [7] Experimental [6] Present Theory (DFT-LDA) [3] Theory (DFT-GGA) [3] Theory (FP-LAPW with GGA) [3] Theory (FP-LAPW with GGA) [36] Theory (FP-LAPW with GGA) [15] Experimental [37] Experimental [38] Experimental [39] The energy band structures calculated for SnS and GeS are shown in Fig. 1.…”

Section: Ges Presentmentioning

confidence: 99%

Mechanical, electronic, and optical properties of the A₄B₆ layered ferroelectrics: ab initio calculation

Koç

Sımsek

Palaz

et al. 2015

Phys. Status Solidi C

View full text Add to dashboard Cite

We have performed a first principles study of the structural, elastic and electronic properties of orthorhombic SnS and GeS compounds using the density functional theory within the local density approximation. The second‐order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, Debye temperature, and hardness have also been estimated in the present work. All of the calculated modulus and Poisson's ratio for SnS were less than the same parameters for GeS. Our calculations have discovered the large anisotropy of elastic parameters in the (100) and (010)‐planes for both compounds. The band structures of orthorhombic SnS and GeS have been calculated along high symmetry directions in the first Brillouin zone (BZ). The calculation results for the band gap of Sn(Ge)S gave Eg = 0.256 eV (0.852 eV) and has an indirect character for an interband transition. The real and imaginary parts of dielectric functions and (by using these results) the optical constant such as energy‐loss function, the effective number of valance electrons and the effective optical dielectric constant were calculated. All of the principal features and singularities of the dielectric functions for both compounds were found in the energy region between 2 eV and 20 eV. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

“…2). From the absorption and photoconductivity spectra of GeS [20,21, 261 and GeSe [24] it was determined that E , = E,. As is seen from Fig.…”

Section: --mentioning

confidence: 99%

Optical spectra and energy band structure of layer‐type A^IVB^VI compounds

Valiukonis

Guseinova

Keivaitb

et al. 1986

Physica Status Solidi (b)

134

View full text Add to dashboard Cite

The electroreflectance and absorption spectra as well as the hydrostatic pressure dependence of the fundamental absorption edge of GeS, GeSe, SnS, and SnSe crystals are investigated in polarized light. The lowest direct energy gaps are found to be 1V1— 1V1 (E | | a) and 1Λ4— 1Λ4 (E || b) for Ge and Sn monochalcogenides, respectively. The pressure coefficient of the energy gap 1Λ4— 1Λ4 dE/AP = = — (1.3 ± 0.1) × 10−4 eV/MPa of SnSe and SnS is almost twice larger than that of the gap 1V1— 1V1 in GeSe, GeS, and SnSe. On the basis of these investigations, different absorption mechanisms responsible for the fundamental absorption edge are discussed.

show abstract

Optical absorption band edge in single-crystal GeS

Cited by 67 publications

References 11 publications

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

Mechanical, electronic, and optical properties of the A₄B₆ layered ferroelectrics: ab initio calculation

Optical spectra and energy band structure of layer‐type A^IVB^VI compounds

Contact Info

Product

Resources

About

Optical absorption band edge in single-crystal GeS

Cited by 67 publications

References 11 publications

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

Polarized Band‐Edge Emission and Dichroic Optical Behavior in Thin Multilayer GeS

Mechanical, electronic, and optical properties of the A4B6 layered ferroelectrics: ab initio calculation

Optical spectra and energy band structure of layer‐type AIVBVI compounds

Contact Info

Product

Resources

About

Mechanical, electronic, and optical properties of the A₄B₆ layered ferroelectrics: ab initio calculation

Optical spectra and energy band structure of layer‐type A^IVB^VI compounds