Nanostructured surfaces

In situ controlled reversible transformations of As56Se44 nanolayers for application as active media in all optical signal processing systems
O.B. Kondrat1, R.M. Holomb1, O.O. Kondrat2, A. Csik3, V. Takats3, M. Veres4, M Vondráček5, N. Tsud6, V. Matolin6, K.C. Prince7 and V.M. Mitsa1
1 Uzhhorod National University, Pidhirna Str., 46, 88000 Uzhhorod, Ukraine.
E-mail: o.b.kondrat@gmail.com
2 Lviv Polytechnic National University, 12, Stepan Bandera street, 79013, Lviv, Ukraine
3 Institute for Nuclear Research, Hungarian Academy of Sciences, H-4001 Debrecen, Hungary.
4 Wigner Research Centre for Physics, Hungarian Academy of Sciences, 1121 Budapest, Hungary.
5 Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, CZ-182 21 Praha 8, Czech Republic.
6 Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8, Czech Republic.
7 Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, Strada Statale 14, km 163.5, 34149 Basovizza (Trieste), Italy

The As56Se44 nanolayers were deposited onto silicon substrates in situ by ordinary thermal evaporation of bulk glass powder at a temperature (T) of 220 °C [1]. Thermal annealing of as-prepared films was performed at Tan~100 °C during 0.5 h. A green diode laser operating at wavelength of 532 nm (corresponding photon energy of ~2.33 eV) was used for in situ modification of the surface structure of annealed nanolayers. It was found that in situ above-bandgap laser illumination stimulates diffusion processes in As56Se44 nanolayers and leads to formation of new structural units (s.u.) with homopolar Se-Se and As-As bonds. The effect of ordering in the structure of illuminated As-Se films during second step of thermal annealing was detected. The appearance of homopolar bonds in the structure of As-Se film surface after second laser illumination were established. Results show that the structural changes of As-Se nanolayers is fully reversible during the cycles of thermal annealing and laser illumination.
1.	O.B. Kondrat, R.M. Holomb, A. Csik, et al. Reversible structural changes of in situ prepared As40Se60 nanolayers studied by XPS spectroscopy // Appl Nanosci (2018). https://doi.org/10.1007/s13204-018-0771-3.