Nanooptics and photonics

Nanosize defect layers in arsenic-implanted and annealed HgCdTe epitaxial films studied with TEM
O.Yu. Bonchyk1, H.V. Savytskyy1, I.I. Izhnin2, K.D. Mynbaev3, A.G. Korotaev4,
A.V. Voitsekhovskii4, O.I. Fitsych2, V.S. Varavin5, S.A. Dvoretsky4,5,
N.N. Mikhailov5, M.V. Yakushev5, Y. Morgiel6, Z. Swiatek6
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 Scientific Research Company “Electron-Carat”, Stryjska St. 202, Lviv 79031, Ukraine
3 Ioffe Institute, Polytekhnicheskaya St. 26, 194021, Saint- Petersburg, Russia
4 Tomsk State University, Lenina Av. 36, Tomsk 634050, Russia
5 A.V. Rzhanov Institute of Semiconductor Physics, SB RAS, ac. Lavrentieva Av. 13, 630090 Novosibirsk, Russia
6 Institute of Metallurgy and Material Science PAN, Reymonta St. 25, 30-059 Krakow, Poland

We report on the results of the study of defect structure of molecular-beam epitaxy-grown epitaxial films of Hg1-хCdхTe (х=0.2, 0.3) implanted with arsenic ions with 190 and 350 keV energy and 1014 cm-2 fluence and subjected to subsequent activation annealing in saturated mercury pressure (350 0C, 2h and 220 0C, 24 h). The microstructure observations were performed with transmission electron microscopy in bright field and high-resolution modes. It was found that after the implantation radiation-damaged area in all the studied samples consisted of three characteristic layers, including a sub-surface layer with low defect density, a deeper layer with big dislocation loops and a deeply buried layer with small dislocation loops. After activation annealing we observed two possible scenarios of the reconstruction of the defect structure. In accordance with the first scenario, the layers containing big and small dislocation loops transformed into a layer with high density of single dislocations. In accordance with the second scenario, full annihilation of dislocation loops occurred and the defect structure of the annealed sample became similar to that of the as-grown sample with most typical defect being a low density single dislocation.