Nanooptics and photonics

Srucrural defects study of HgTe/CdHgTe quantum wells
O.Yu. Bonchyk1, H.V. Savytskyy1, Z. Swiatek2, Y. Morgiel2, I.I. Izhnin3, A.V. Voitsekhovskii4, A.G. Korotaev4,  O.I. Fitsych5, K.D. Mynbaev6            N.N. Mikhailov7,V.S. Varavin7, S.A. Dvoretsky4,7

1 Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU, Naukova St. 3b, 79060 Lviv, Ukraine
E-mail: bonchyk@ukr.net
2 Institute of Metallurgy and Material Science PAN, Reymonta St. 25, 30-059 Krakow, Poland
3 Scientific Research Company “Electron-Carat”, Stryjska St. 202, Lviv 79031, Ukraine.
4 Tomsk State University, Lenina Av., 36, Tomsk 634050, Russia
5 Hetman Petro Sahaidachny National Army Academy, Gvardijska St. 32, 79012 Lviv, Ukraine
6 Ioffe Institute, Politekhnicheskaya St. 26, 194021,St. Petersburg, Russia
7 A.V. Rzhanov Institute of Semiconductor Physics, SB RAS, ac. Lavrentieva Av. 13, 630090 Novosibirsk , Russia

HgTe/CdHgTe quantum wells (QWs) are intensively studied due to their unique physical properties and the resulting applications. For example, such QWs with the inverted band ordering (which appears when HgTe QW width exceeds 6.3 nm) were identified as the first 2D topological insulators, while narrow-bandgap HgTe/CdHgTe QWs represent interest for various applications in far-infrared and terahertz optoelectronics.
Despite the increasing number of papers devoted to the studies of the physical properties of HgTe/CdHgTe QWs, defects of crystal structure in such QWs, to the best of our knowledge, have not been studied in detail. We present the results of High-Resolution Transmission Electron Microscopy study of two single HgTe/CdHgTe QWs with different designs, namely, with and without an additional CdHgTe buffer layer placed between the CdTe buffer and HgTe/CdHgTe QW system in a GaAs/ZnTe/CdTe/Hg(Cd)Te heterostructure. The effect of this buffer layer on the crystalline quality of QWs and barrier layers was investigated and defects in both type of layers and at their interfaces, namely, dislocations, dislocation loops and crystal lattice deformations, were revealed and identified.