Study of the influence of laser wavelength on the dichroism effect in ZnO:Ag films

ZnO:Ag films are used as photoabsorbing layers in plasmonic photodetectors. The use of laser radiation in the manufacture of photodetectors allows one to control the parameters of the plasmon resonance peak and change the range of spectral sensitivity of the device. Known studies on laser action on similar photoabsorbing films with nanoparticles pay little attention to the dichroism effect arising as a result of laser action. In the presence of dichroism, the efficiency of a plasmonic photodetector depends on the polarization of the detected radiation. The aim of this work is to study the dichroism effect arising in ZnO:Ag films under the action of femtosecond laser radiation with wavelengths near the plasmon resonance of nanoparticles and far from it. To obtain the dichroism effect in the films, laser pulses with a wavelength near the plasmon resonance of nanoparticles (515 ± 5 nm) and far from it (1030 ± 5 nm) were used. Linearly polarized pulses of 224 ± 15 fs duration and 200 kHz repetition rate were used. Transmission spectra of linearly polarized light by areas of ZnO:Ag films modified by laser radiation were obtained using a spectrophotometer microscope. The size, concentration, shape and arrangement of nanoparticles in the films, and the surface morphology of zinc oxide (ZnO) films were studied using electron microscopy methods. It was shown that laser radiation with a wavelength near the plasmon resonance of nanoparticles with an energy density in a pulse higher than 43 ± 0.5 mJ/cm² leads to the appearance of a dichroism effect in the films. The occurrence of this effect is associated with the reorientation of nanoparticles. Laser action leads to a reorientation of the initially chaotic arrangement of nanoparticles in the direction parallel to the polarization vector of the laser radiation. The highest value of the linear dichroism is achieved in the region of plasmon resonance wavelengths of 515 ± 5 nm at a radiation energy density of 66 ± 0.5 mJ/cm². A further increase in the energy density leads to a decrease in dichroism due to the return of chaotic orientation. The effect of radiation with a wavelength far from the plasmon resonance of 1030 ± 5 nm with equivalent energy densities does not lead to a reorientation of nanoparticles and, as a consequence, the change in the linear dichroism value is significantly lower. According to the proposed hypothesis, the differences between the results of laser exposure are associated with different mechanisms of radiation absorption in the material. Radiation with a wavelength of 515 ± 5 nm is absorbed by nanoparticles. In the case of linear polarization of radiation, ionization of nanoparticles and their reorientation parallel to the polarization vector occur. At a wavelength of 1030 ± 5 nm, radiation is absorbed by the ZnO matrix. This leads to heating of the film, heat transfer to the nanoparticles, as a result of which the process of reorientation of nanoparticles parallel to the polarization vector is complicated, and the dichroism effect is much less pronounced. The results of the study can be used in the design and manufacture of photodetectors due to the identified possibility of shifting the peak of plasmon resonance of nanoparticles in the photoabsorbing layer of the photodetector. Control of the dichroism effect allows controlling the sensitivity range of detectors.

1. Klochko N.P., Klepikova K.S., Khrypunova I.V., Kopach V.R., Tyukhov I.I., Petrushenko, S.I., Dukarov S.V., Sukhov V.M., Kirichenko M.V., Khrypunova A.L. Solution-processed flexible broadband ZnO photodetector modified by Ag nanoparticles // Solar Energy. 2022. V. 232. P. 1–11. https://doi.org/10.1016/j.solener.2021.12.051

2. Tang H., Chen C.J., Huang Z., Bright J., Meng G., Liu R.S., Wu N. Plasmonic hot electrons for sensing, photodetection, and solar energy applications: A perspective // The Journal of Chemical Physics. 2020. V. 152. N 22. https://doi.org/10.1063/5.0005334

3. Alharbi A.M., Ahmed N.M., Rahman A.A., Azman N.Z.N., Algburi S., Wadi I.A., Binzowaimil A.M., Aldaghri O., Ibnaouf K.H. Development of ZnO and Si semiconductor-based ultraviolet photodetectors enhanced by laser-ablated silver nanoparticles // Photonics and Nanostructures-Fundamentals and Applications. 2024. V. 58. P. 101228. https://doi.org/10.1016/j.photonics.2024.101228

4. Koleva M.E., Nedyalkov N.N., Nikov Ru., Nikov Ro., Atanasova G., Karashanova D., Nuzhdin V.I., Valeev V.F., Rogov A.M., Stepanov A.L. Fabrication of Ag/ZnO nanostructures for SERS applications // Applied Surface Science. 2020. V. 508. P. 145227. https://doi.org/10.1016/j.apsusc.2019.145227

5. Jain S., Medlin W., Uprety S., Isaacs-Smith T., Olsson T., Davis J., Burrows S., Chumley S., Park M., Laurent G.M. Nanosecond-laser annealing of zinc oxide thin-films: The effect of the laser wavelength and fluence // Thin Solid Films. 2024. V. 791. P. 140236. https://doi.org/10.1016/j.tsf.2024.140236

6. Varlamov P.V., Sergeev M.M., Zakoldaev R.A., Grigoryev E.A. Femtosecond wavelength influence on TiO2: Ag film spectral changes: Comparative study // Materials Letters. 2022. V. 323. P. 132605. https://doi.org/10.1016/j.matlet.2022.132605

7. Andreeva Y., Sharma N., Rudenko A., Mikhailova J., Sergeev M., Veiko V.P., Vocanson F., Lefkir Y., Destouches N., Itina T.E. Insights into ultrashort laser-driven Au: TiO2 nanocomposite formation // The Journal of Physical Chemistry C. 2020. V. 124. N 18. P. 10209–10219. https://doi.org/10.1021/acs.jpcc.0c01092

8. Miranda M.H.G., Falcão-Filho E.L., Rodrigues Jr. J.J., de Araújo C.B., Acioli L.H. Ultrafast light-induced dichroism in silver nanoparticles // Physical Review B. 2004. V. 70. N 16. P. 161401. https://doi.org/10.1103/PhysRevB.70.161401

9. Stalmashonak A., Seifert G., Graener H. Spectral range extension of laser-induced dichroism in composite glass with silver nanoparticles // Journal of Optics A: Pure and Applied Optics. 2009. V. 11. N 6. P. 065001. https://doi.org/10.1088/1464-4258/11/6/065001

10. Gresko V.R., Sergeev M.M., Smirnova V.V., Dolgopolov A.D., Sokura L.A., Kostyuk G.K., Grigoryev E.A. Femtosecond laser modification of the ZnO:Ag sol-gel films within dichroism emergence. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2024, vol. 24, no. 3, pp. 384– 398. (in Russian). https://doi.org/10.17586/2226-1494-2024-24-3-384-398

11. Liu J.M. Simple technique for measurements of pulsed Gaussian-beam spot sizes // Optics letters. 1982. V. 7. N 5. P. 196–198. https://doi.org/10.1364/OL.7.000196

12. Yeshchenko O.A., Dmitruk I.M., Alexeenko A.A., Kotko A.V., Verdal J., Pinchuk A.O. Size and temperature effects on the surface plasmon resonance in silver nanoparticles // Plasmonics. 2012. V. 7. P. 685–694. https://doi.org/10.1007/s11468-012-9359-z

13. Shirshneva-Vaschenko E.V., Sokura L.A., Baidakova M.V., Yagovkina M.A., Snezhnaia Z.G., Shirshnev P.S., Romanov A.E. Study of the influence of the ZnO: Al polycrystalline film morphology on the silver nanoparticles formation // Journal of Physics: Conference Series. 2019. V. 1400. N 5. P. 055026. https://doi.org/10.1088/1742-6596/1400/5/055026

14. Kuptsova A.O., Kuptsov G.V., Petrov V.A., Atuchin V.V., Petrov V.V. Laser scanning method for time-resolved measurements of wavefront distortion introduced by active elements in high-power laser amplifiers // Photonics. 2024. V. 11. N 8. P. 748. https://doi.org/10.3390/photonics11080748

15. Shirshneva-Vaschenko E.V., Sokura L.A., Shirshnev P.S., Kirilenko D.A., Snezhnaia Z.G., Bauman D.A., Bougrov V.E., Romanov A.E. Preparation of transparent N-Zno: Al/P-Cualcro2 Heterojunction Diode by Sol-Gel technology // Reviews on Advanced Materials Science. 2018. V. 57. N 2. P. 167–174. https://doi.org/10.1515/rams-2018-0061

16. Buividas R., Mikutis M., Juodkazis S. Surface and bulk structuring of materials by ripples with long and short laser pulses: Recent advances // Progress in Quantum Electronics. 2014. V. 38. N 3. P. 119–156. https://doi.org/10.1016/j.pquantelec.2014.03.002

17. Zamfirescu M., Dinescu A., Danila M., Socol G., Radu C. The role of the substrate material type in formation of laser induced periodical surface structures on ZnO thin films // Applied surface science. 2012. V. 258. N 23. P. 9385–9388. https://doi.org/10.1016/j.apsusc.2012.01.089

18. Sokura L.A., Snezhnaia Zh.G., Nevedomskiy V.N., Shirshneva-Vaschenko E.V., Romanov A.E. Ordering mechanism of silver nanoparticles synthesized in a ZnO: Al polycrystalline film by sol gel method // Journal of Physics: Conference Series. 2020. V. 1695. P. 012034. https://doi.org/10.1088/1742-6596/1695/1/012034

19. Kaempfe M., Seifert G., Berg K.-J., Hofmeister H., Graener H. Polarization dependence of the permanent deformation of silver nanoparticles in glass by ultrashort laser pulses // The European Physical Journal D-Atomic, Molecular, Optical and Plasma Physics. 2001. V. 16. P. 237–240. https://doi.org/10.1007/s100530170100