N.V. Vishnyakov – Ph.D.(Eng.), Associate Professor, 

Department «Micro- and nanoelectronics», Ryazan State Radio Engineering University named after V.F. Utkin E-mail: rcpm-rgrtu@yandex.ru; rcpm@rsreu.ru

S.P. Vikhrov – Honored Scientist of RF, Dr.Sc.(Phys.-Math.), Professor, Main Research Scientist, SRI «Foton» of Ryazan State Radio Engineering University named after V.F. Utkin

E-mail: vikhrovsergey@mail.ru

N.M. Tolkach – Ph.D.(Phys.-Math.), Junior Research Scientist,  Institute of Advanced Materials and Technologies of MIET Е-mail: n.m.tolkach@gmail.com

Materials with phase transitions, in particular, chalcogenide glassy semiconductors of the Ge-Sb-Te (GST) system, are promising for integral optical systems. GST materials are having a reversible, fast, and low-energy phase transition for substantially different optical properties of amorphous and crystalline states. A development of diagnostic methods for a study of these materials is relevant. In the article results and technique of complex diagnostics of local areas of the GST film which allows to carry out studies by photometry, Raman spectroscopy, atomic force microscopy, optical microscopy, laser modification in a single measuring cycle were presented. The algorithm for calculating complex refractive index from values of reflectance and transmittance ability at normal incidence of optical beams was provided. Phase states of local areas of the GST film were determined using this algorithm and corresponded to results of Raman spectrometry. A decrease in the peak intensity in Raman shift region – 130 cm−1 for the amorphous GST film in Raman spectra was observed. This is due to transition of Ge atom from octahedral to tetrahedral environment of Te atoms and a decrease in the hardness of Ge-Te atomic bonds. The peak in region of Raman shift – 145 cm−1 was corresponded to vibrations of Sb-Te atomic bonds. Parameters of laser pulses with a wavelength of 403 nm were found for amorphization and crystallization of the GST film material. Amorphization was observed for a laser pulse with a duration –  = 10 ns, a period – T = 200 ns and an energy exposure – H0 = 3.2 ± 0.03 nJ / μm2. Crystallization was observed for a laser pulse with a duration –  = 30 ns, a period – T = 200 ns and an energy exposure – H0 = 2.8 ± 0.03 nJ / μm2.

1. Vishnyakov N.V., Provotorov P.S., Tolkach N.M. Optimizatsiya parametrov tonkoplenochnoi struktury na osnove Ge2Sb2Te5 dlya opticheskikh pereklyuchatelei. Vestnik Ryazanskogo gosudarstvennogo radiotekhnicheskogo universiteta. 2018. № 4-2 (66). S. 2−8. DOI: 10.21667/1995-4565-2018-66-4-2-2-8. (in Russian)
2. Nguyen H.P., Kozyukhin S.A., Pevtsov A.B. Influence of bismuth on the optical properties of Ge2Sb2Te5 thin films. Semiconductors. 2014. T. 48. № 5. P. 577−583. DOI: 10.1134/S1063782614050169.
3. Sherchenkov A.A., Babich A.V., Lazarenko P.I. Vliyanie legirovaniya In na svoistva tonkikh plenok Ge2Sb2Te5, primenyaemykh v ustroistvakh fazovoi pamyati. Vestnik Ryazanskogo gosudarstvennogo radiotekhnicheskogo universiteta. 2012. № 4-2 (42). S. 81−88. (in Russian)
4. Kozyukhin S.A., Sherchenkov A.A. Perspektivy primeneniya khalkogenidnykh splavov v elementakh fazovoi pamyati. Vestnik Ryazanskogo gosudarstvennogo radiotekhnicheskogo universiteta. 2009. № 4-S1 (30). S. 81−87. (in Russian)
5. Kozyukhin S.A., Lazarenko P.I., Vorobyov Y.V., Savelyev M.S., Polokhin A.A., Glukhenkaya V.B., Sherchenkov A.A., Gerasimenko A.Y. Laser-induced modification of amorphous GST225 phase change materials. Matériaux & Techniques. 2018. V. 180070. P. 1−6. DOI: 10.1051/mattech/2019008.
6. Siegel J., Gawelda W., Puerto D., Dorronsoro C., Solis J., Afonso C.N., De Sande J.C.G., Bez R., Pirovano A., Wiemer C. Amorphization dynamics of Ge2Sb2Te5 films upon nano- and femtosecond laser pulse irradiation. Journal of Applied Physics. 2008. T. 103. № 023516. P. 1−7. DOI: 10.1063/1.2836788.
7. Fuxi G., Yang W. Laser Pulse-Induced Amorpization Process. Data Storage at the Nanoscale: Advances and Applications. Taylor & Francis Group. 2015. P. 190−194. DOI: 10.1201/b18094.
8. Born M., Wolf E. An absorbing film on a transparent substrate. Principles of optics. 7th ed. Cambridge: Cambridge University Press. 2003. P. 753−754. DOI: 10.1017/CBO9781139644181.023.
9. Rodionov S.A., Gutman E.I. Optimizatsiya nelineinykh sistem. V kn. «Raschet i konstruirovanie mekhanizmov i detalei priborov». L.: Mashinostroenie. 1975. S. 5−37. (in Russian)
10. Avachev A.P., Avacheva T.G., Vishnyakov N.V., Vorobev Yu.V., Gudzev V.V., Maltsev M.V., Rybin N.B. Issledovanie sostava i tolshchiny plenok Ge–Sb–Te s pomoshchyu rentgenovskogo analiza i atomno-silovoi mikroskopii. Vestnik Ryazanskogo gosudarstvennogo radiotekhnicheskogo universiteta. 2013. № 4-3 (46). S. 79−82. (in Russian)
11. Kolobov A.V., Fons P., Tominaga J., Frenkel A.I., Ankudinov A.L., Yannopoulos S.N., Andrikopoulos K.S. and Uruga T. Why PhaseChange Media Are Fast and Stable: A New Approach to an Old Problem. Japanese Journal of Applied Physics. 2005. V. 44. № 5B. P. 3345−3349. DOI: 10.1143/JJAP.44.3345.
12. Abrikosov N.K., Danilova-Dobryakova G.T. An investigation of the structural diagram of Sb2Te3-GeTe. Neorg. Mater. 1965. V. 1. № 2. P. 204−207.
13. Avachev A.P., Vikhrov S.P., Vishnyakov N.V., Mitrofanov K.V., Kozyukhin S.A., Terukov E.I. Phase transitions in thin Ge2Sb2Te5 chalcogenide films according to Raman spectroscopy data. Semiconductors. 2012. V. 46. № 5. P. 591−594. DOI: 10.1134/S1063782612050041.