Indium(II) selenide (InSe) is an inorganic compound composed of indium and selenium. It is a III-VI layered semiconductor. The solid has a structure consisting of two-dimensional layers bonded together only by van der Waals forces. Each layer has the atoms in the order Se-In-In-Se.[2]
Indium(II) selenide can be formed via a number of different methods. A method to make the bulk solid is the Bridgman/Stockbarger method, in which the elements indium and selenium are heated to over 900 °C in a sealed capsule, and then slowly cooled over about a month.[4] Another method is electrodeposition from a water solution of indium(I) sulfate and selenium dioxide.[5]
Properties
There are three polytopes or crystal forms. β, ε are hexagonal with unit cells spanning two layers. γ has rhombohedral crystal system, with the unit cell including four layers.[2]
β-Indium(II) selenide can be exfoliated into two-dimensional sheets using sticky tape. In a vacuum these form smooth layers. However, when exposed to air, the layers become corrugated because of chemisorption of air molecules.[6] Exfoliation can also take place in isopropanol liquid.[7]
Indium (II) selenide is stable in ambient conditions of oxygen and water vapour, unlike many other semiconductors.[2]
polytope
space group
unit cell
band gap
eV
β
P63/mmc
a=4.005 c=16.660 Z=4
direct
1.28
γ
R3m
a=7.1286 Å, c=19.382 Å and Z=6
direct
1.29
ε
P6m2
indirect
1.4
Doping
The properties of indium(II) selenide can be varied by way of altering the exact ratio of elements from 1:1, creating vacancies. It is hard to get an exact equality. The properties can be compensated by transition element doping. Other elements that can be included in small concentrations are boron,[8]silver,[9] and cadmium.[10]
References
^Teena, M.; Kunjomana, A. G. (April 2018). "Crystal shape engineering and studies on the performance of vapour deposited InSe platelets". Journal of Materials Science: Materials in Electronics. 29 (7): 5536–5547. doi:10.1007/s10854-018-8522-5. S2CID103682866.
^Dmitriev, A. I.; Vishnjak, V. V.; Lashkarev, G. V.; Karbovskyi, V. L.; Kovaljuk, Z. D.; Bahtinov, A. P. (March 2011). "Investigation of the morphology of the van der Waals surface of the InSe single crystal". Physics of the Solid State. 53 (3): 622–633. Bibcode:2011PhSS...53..622D. doi:10.1134/S1063783411030085. S2CID121113583.
^Petroni, Elisa; Lago, Emanuele; Bellani, Sebastiano; Boukhvalov, Danil W.; Politano, Antonio; Gürbulak, Bekir; Duman, Songül; Prato, Mirko; Gentiluomo, Silvia; Oropesa-Nuñez, Reinier; Panda, Jaya-Kumar; Toth, Peter S.; Del Rio Castillo, Antonio Esau; Pellegrini, Vittorio; Bonaccorso, Francesco (June 2018). "Liquid-Phase Exfoliated Indium-Selenide Flakes and Their Application in Hydrogen Evolution Reaction". Small. 14 (26): 1800749. arXiv:1903.08967. doi:10.1002/smll.201800749. PMID29845748. S2CID44172633.
^Ertap, Hüseyin; Karabulut, Mevlut (5 December 2018). "Structural and electrical properties of boron doped InSe single crystals". Materials Research Express. 6 (3): 035901. doi:10.1088/2053-1591/aaf2f6. S2CID105206868.
^Gürbulak, Bekir; Şata, Mehmet; Dogan, Seydi; Duman, Songul; Ashkhasi, Afsoun; Keskenler, E. Fahri (November 2014). "Structural characterizations and optical properties of InSe and InSe:Ag semiconductors grown by Bridgman/Stockbarger technique". Physica E: Low-dimensional Systems and Nanostructures. 64: 106–111. Bibcode:2014PhyE...64..106G. doi:10.1016/j.physe.2014.07.002.