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Author |
Yayak, Y.O.; Sozen, Y.; Tan, F.; Gungen, D.; Gao, Q.; Kang, J.; Yagmurcukardes, M.; Sahin, H. |
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Title |
First-principles investigation of structural, Raman and electronic characteristics of single layer Ge3N4 |
Type |
A1 Journal article |
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Year  |
2022 |
Publication |
Applied surface science |
Abbreviated Journal |
Appl Surf Sci |
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Volume |
572 |
Issue |
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Pages |
151361 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
By means of density functional theory-based first-principle calculations, the structural, vibrational and electronic properties of single-layer Ge3N4 are investigated. Structural optimizations and phonon band dispersions reveal that single-layer ultrathin form of Ge3N4 possesses a dynamically stable buckled structure with large hexagonal holes. Predicted Raman spectrum of single-layer Ge3N4 indicates that the buckled holey structure of the material exhibits distinctive vibrational features. Electronic band dispersion calculations indicate the indirect band gap semiconducting nature of single-layer Ge3N4. It is also proposed that single-layer Ge3N4 forms type-II vertical heterostructures with various planar and puckered 2D materials except for single-layer GeSe which gives rise to a type-I band alignment. Moreover, the electronic properties of single-layer Ge3N4 are investigated under applied external in-plane strain. It is shown that while the indirect gap behavior of Ge3N4 is unchanged by the applied strain, the energy band gap increases (decreases) with tensile (compressive) strain. |
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Place of Publication |
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Wos |
000723664000006 |
Publication Date |
2021-10-01 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0169-4332 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.7 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 6.7 |
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Call Number |
UA @ admin @ c:irua:184752 |
Serial |
6993 |
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Author |
Yagmurcukardes, M.; Sozen, Y.; Baskurt, M.; Peeters, F.M.; Sahin, H. |
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Title |
Interface-dependent phononic and optical properties of GeO/MoSO heterostructures |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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Volume |
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Issue |
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Pages |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The interface-dependent electronic, vibrational, piezoelectric, and optical properties of van der Waals heterobilayers, formed by buckled GeO (b-GeO) and Janus MoSO structures, are investigated by means of first-principles calculations. The electronic band dispersions show that O/Ge and S/O interface formations result in a type-II band alignment with direct and indirect band gaps, respectively. In contrast, O/O and S/Ge interfaces give rise to the formation of a type-I band alignment with an indirect band gap. By considering the Bethe-Salpeter equation (BSE) on top of G(0)W(0) approximation, it is shown that different interfaces can be distinguished from each other by means of the optical absorption spectra as a consequence of the band alignments. Additionally, the low- and high-frequency regimes of the Raman spectra are also different for each interface type. The alignment of the individual dipoles, which is interface-dependent, either weakens or strengthens the net dipole of the heterobilayers and results in tunable piezoelectric coefficients. The results indicate that the possible heterobilayers of b-GeO/MoSO asymmetric structures possess various electronic, optical, and piezoelectric properties arising from the different interface formations and can be distinguished by means of various spectroscopic techniques. |
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Wos |
000738899600001 |
Publication Date |
2021-12-09 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2040-3364 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
7.367 |
Times cited |
2 |
Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 7.367 |
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Call Number |
UA @ admin @ c:irua:184722 |
Serial |
6998 |
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Author |
Sozen, Y.; Yagmurcukardes, M.; Sahin, H. |
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Title |
Vibrational and optical identification of GeO₂ and GeO single layers : a first-principles study |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical Chemistry Chemical Physics |
Abbreviated Journal |
Phys Chem Chem Phys |
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Volume |
23 |
Issue |
37 |
Pages |
21307-21315 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
In the present work, the identification of two hexagonal phases of germanium oxides (namely GeO2 and GeO) through the vibrational and optical properties is reported using density functional theory calculations. While structural optimizations show that single-layer GeO2 and GeO crystallize in 1T and buckled phases, phonon band dispersions reveal the dynamical stability of each structure. First-order off-resonant Raman spectral predictions demonstrate that each free-standing single-layer possesses characteristic peaks that are representative for the identification of the germanium oxide phase. On the other hand, electronic band dispersion analysis shows the insulating and large-gap semiconducting nature of single-layer GeO2 and GeO, respectively. Moreover, optical absorption, reflectance, and transmittance spectra obtained by means of G(0)W(0)-BSE calculations reveal the existence of tightly bound excitons in each phase, displaying strong optical absorption. Furthermore, the excitonic gaps are found to be at deep UV and visible portions of the spectrum, for GeO2 and GeO crystals, with energies of 6.24 and 3.10 eV, respectively. In addition, at the prominent excitonic resonances, single-layers display high reflectivity with a zero transmittance, which is another indication of the strong light-matter interaction inside the crystal medium. |
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Place of Publication |
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Wos |
000697364300001 |
Publication Date |
2021-09-02 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1463-9076; 1463-9084 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.123 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 4.123 |
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Call Number |
UA @ admin @ c:irua:181571 |
Serial |
7044 |
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Author |
Sozen, Y.; Eren, I.; Ozen, S.; Yagmurcukardes, M.; Sahin, H. |
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Title |
Interaction of Ge with single layer GaAs : from Ge-island nucleation to formation of novel stable monolayers |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Applied Surface Science |
Abbreviated Journal |
Appl Surf Sci |
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Volume |
505 |
Issue |
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Pages |
144218-7 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
In this study, reactivity of single-layer GaAs against Ge atoms is studied by means of ab initio density functional theory calculations. Firstly, it is shown that Ge atoms interact quite strongly with the GaAs layer which allows the formation of Ge islands while it hinders the growth of detached germanene monolayers. It is also predicted that adsorption of Ge atoms on GaAs single-layer lead to formation of two novel stable single-layer crystal structures, namely 1H-GaGeAs and 1H(A)-GaGeAs. Both the total energy optimizations and the calculated vibrational spectra indicate the dynamical stability of both single layer structures. Moreover, although both structures crystallize in 1H phase, 1H-GaGeAs and 1H(A)-GaGeAs exhibit distinctive vibrational features in their Raman spectra which is quite important for distinguishing the structures. In contrast to the semiconducting nature of single-layer GaAs, both polytypes of GaGeAs exhibit metallic behavior confirmed by the electronic band dispersions. Furthermore, the linear-elastic constants, in-plane stiffness and Poisson ratio, reveal the ultrasoft nature of the GaAs and GaGeAs structures and the rigidity of GaAs is found to be slightly enhanced via Ge adsorption. With their stable, ultra-thin and metallic properties, predicted single-layer GaGeAs structures can be promising candidates for nanoscale electronic and mechanical applications. |
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Wos |
000510846500026 |
Publication Date |
2019-11-02 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0169-4332 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
6.7 |
Times cited |
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Open Access |
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Notes |
; Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid eInfrastructure). H.S. acknowledges financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) under the project number 117F095. H.S. acknowledges support from Turkish Academy of Sciences under the GEBIP program. This work is supported by the Flemish Science Foundation (FWO-Vl) by a postdoctoral fellowship (M.Y.). ; |
Approved |
Most recent IF: 6.7; 2020 IF: 3.387 |
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Call Number |
UA @ admin @ c:irua:167733 |
Serial |
6548 |
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Author |
Eren, I.; Ozen, S.; Sozen, Y.; Yagmurcukardes, M.; Sahin, H. |
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Title |
Vertical van der Waals heterostructure of single layer InSe and SiGe |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
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Volume |
123 |
Issue |
51 |
Pages |
31232-31237 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
We present a first-principles investigation on the stability, electronic structure, and mechanical response of ultrathin heterostructures composed of single layers of InSe and SiGe. First, by performing total energy optimization and phonon calculations, we show that single layers of InSe and SiGe can form dynamically stable heterostructures in 12 different stacking types. Valence and conduction band edges of the heterobilayers form a type-I heterojunction having a tiny band gap ranging between 0.09 and 0.48 eV. Calculations on elastic-stiffness tensor reveal that two mechanically soft single layers form a heterostructure which is stiffer than the constituent layers because of relatively strong interlayer interaction. Moreover, phonon analysis shows that the bilayer heterostructure has highly Raman active modes at 205.3 and 43.7 cm(-1), stemming from the out-of-plane interlayer mode and layer breathing mode, respectively. Our results show that, as a stable type-I heterojunction, ultrathin heterobilayer of InSe/SiGe holds promise for nanoscale device applications. |
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Corporate Author |
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Place of Publication |
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Language |
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Wos |
000505632900050 |
Publication Date |
2019-12-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1932-7447; 1932-7455 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.536 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 4.536 |
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Call Number |
UA @ admin @ c:irua:165718 |
Serial |
6332 |
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