WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
Browse
Search Results
Now showing 1 - 2 of 2
Article Citation - WoS: 134Citation - Scopus: 137Structural, Vibrational, and Electronic Properties of Single-Layer Hexagonal Crystals of Group Iv and V Elements(American Physical Society, 2018) Özdamar, Burak; Özbal, Gözde; Çınar, Mustafa Neşet; Sevim, Koray; Kurt, Gizem; Kaya, Birnur; Sevinçli, HaldunUsing first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula A2B2, where A and B belong to groups IV and V, respectively (A=C, Si, Ge, Sn, Pb; B=N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices P6m2 and P3m1 are shown to be dynamically stable, named as α- and β -phases correspondingly. Both phases have similar cohesive energies, and the α phase is found to be energetically favorable for structures except CP, CAs, CSb, and CBi, for which the β phase is favored. The effects of spin-orbit coupling and Hartree-Fock corrections to exchange correlation are included to elucidate the electronic structures. All structures are semiconductors except CBi and PbN, which have metallic character. SiBi, GeBi, and SnBi have direct band gaps, whereas the remaining semiconductor structures have indirect band gaps. All structures have quartic dispersion in their valence bands, some of which make the valence band maximum and resemble a mexican-hat shape. SnAs and PbAs have purely quartic valence band edges, i.e., E-αk4, a property reported for the first time. The predicted materials are candidates for a variety of applications. Owing to their wide band gaps, CP, SiN, SiP, SiAs, GeN, GeP can find their applications in optoelectronics. The relative band positions qualify a number of the structures as suitable for water splitting, where CN and SiAs are favorable at all pH values. Structures with quartic band edges are expected to be efficient for thermoelectric applications.Article Citation - WoS: 171Citation - Scopus: 169Janus Single Layers of In2sse: a First-Principles Study(American Physical Society, 2018) Kandemir, Ali; Şahin, HasanBy performing first-principles calculations, we propose a stable direct band gap semiconductor Janus single-layer structure, In2SSe. The binary analogs of the Janus structure, InS and InSe single layers are reviewed to evince the structural and electronic relation with In2SSe. The structural optimization calculations reveal that a Janus In2SSe single layer has hexagonal geometry like the InS and InSe single layers, which are also its structural analogs. The Janus single layer is dynamically stable, as indicated by the phonon spectrum. The electronic band diagram of the Janus structure shows that an In2SSe single layer is a direct band gap semiconductor, in contrast to its analogs, InS and InSe single layers, which are indirect band gap semiconductors. Nevertheless, it is found that the strain effect on electronic properties of the InS and InSe single layers designates the electronic structure of the Janus single layer. A rough model for the construction of the electronic band diagram of the Janus structures is discussed, and it is indicated that the difference in work functions of chalcogenide sides in the Janus structure determines the construction of the electronic structure. It is found that the Janus structure is a robust direct gap semiconductor under tolerable strain; for that reason, the Janus In2SSe single layer is a candidate for optoelectronic nanodevice applications.