Center for Laser Technologies and Nanoengineering

National Research Foundation of Ukraine Project for the implementation of scientific research and development "Science for the security and sustainable development of Ukraine"

Project title

Optically and acoustically controlled devices for controlling terahertz radiation based on `crystalline and nanocomposite materials.

Project content

The problem the research aimed to solve:

Improving the characteristics of existing THz radiation modulators.

There are two types of optically controlled THz radiation modulators. The first uses a light beam to illuminate the active surface of the device in order to excite free carriers, which leads to a change in the dielectric properties of the device material. The second type of modulators uses controlled light with a two-dimensional grating that illuminates, for example, a silicon wafer [S.Busch et.al. // Optic. Express 2012 37 1391]. This allows for higher resolution and bandwidth and greater modulation depth. This approach may be of interest in the development of millimeter-wave lens antennas [Modern Lens Antennas for Communications Engineering / John Thornton, Kao-Cheng Huang. - Wiley-IEEE Press, 2013. - p.428]. It should be noted that there is a need to develop optically controlled THz radiation modulators of the second type with lower switching times. The principle of such improved modulation on charge density waves was proposed even earlier and is now actively used [Peter J. et.al. // Optics Express 2019 27 1433]. But the disadvantage of this approach is the need to use low temperatures. Therefore, the implementation of such modulators operating under normal conditions is an urgent task.

The object of the project research

Is crystalline materials Si, Ge, BSO, BGO, Se and ITO films, Si:BSO and Si:BGO nanocomposites in the visible, infrared and THz frequency range.

The subject of the project research

Is the optical and quasi-optical properties of selected materials, the influence of optical irradiation and acoustic waves on their electrical properties.

The purpose and main goal of the research:

The main goal of the project is the development and research of optically controlled modulators based on Si, Ge or Se and acoustically controlled modulators based on Bi12GeO20 or Bi12SiO20 in the THz spectral range.

To achieve the goal, it was necessary to perform the following tasks:

Main results

Nanocomposite materials were created based on porous matrices of Si, SiO2, Al2O3 and nanocrystals of Bi12GeO20, Bi12SiO20 filling. Nanoporous structures from saturated aqueous solutions were filled with crystals of the corresponding compounds and nanocrystalline structures were obtained from high-temperature LiNbO3 crystals at a temperature of 925°C on Si and SiO2 matrices. Bi12GeO20 and Bi12SiO20 compounds were introduced into the pores of mesoporous Si matrices by the melt method at high temperatures. Methods of structural and spectroscopic analysis of nanosized compounds newly synthesized in the pores of the parent matrices of Si and SiO2 were further developed.

The optimal thicknesses of crystalline samples were determined according to the optical constants calculated from measurements to achieve the maximum modulation depth of THz radiation at a frequency of 130 GHz. Using chemical etching methods of the surface of semiconductor samples, it was possible to achieve a modulation depth of THz radiation approaching 100%. The efficiency of use was tested and the method of controlling THz radiation by illuminating the sample with powerful optical radiation with different apertures of optical illumination was improved. Different ranges were used: 80-140 GHz and 100-1350 GHz.

A method for optimizing the transmission of photomodulators of the subterahertz frequency range based on semiconductor materials Si and Ge was proposed. Experimental studies were conducted to confirm the optimization of photomodulation in the transmission geometry. The refractive index n and the absorption coefficient α for these materials were calculated based on the measurement of the phase shift of electromagnetic radiation when it passes through air, as well as when the sample under study is introduced into the circuit. The results of the calculations of n and α using this method are compared with the above method, which is based on the inverse and forward Fourier transform and the application of the Henning window. The theoretical method for analyzing the lattice dynamics of newly synthesized substances using the results of a first-principles calculation has also been further developed.

Originality and innovative aspects

For the first time, nanostructures based on BGO and BSO crystals were created on Si matrices at a temperature of 950°C.

For the first time, a study of photoinduced changes in Ge in the reflection and transmission geometries depending on the thickness of the Ge crystal and the intensity of illumination on photomodulation of radiation with a frequency of 130 GHz was carried out.

For the first time, polarized Raman spectra of Bi12GeO20 and Bi12SiO20 crystals were obtained, systematized according to irreducible representations. For this, a special spectroscopic polarization technique was used for these crystals.

For the first time, polarized Raman spectra were calculated from first principles and the experimental spectra were interpreted based on ab initio calculation of lattice dynamics.

For the first time, Raman spectra of the Si:Bi12GeO20 nanocomposite material were measured and analyzed.

Based on the project materials the oral and poster presentations were made at International Conferences:

  1. Andrushchak A.S., Danylov A.B., Balaban O.V., Venhryn B.Ya. Modulators for THz range: principles and materials // 5th International Conference "Actual Problems of Fundamental Science" (APFS-2023). Proceedings. June 01-05, 2023. Lutsk - Svityaz', Ukraine. -P. 13-14.
  2. Shchur Ya., Adamiv V., Teslyuk I, Andrushchak A. Preparation of Bi12GeO20 nanocrystalline structures // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. -P. 55.
  3. Andrushchak N., Vynnyk D., Haiduchok V., Nikolenko A., Adamiv V., Strelchuk V., Syrotynsky O., Andrushchak A. Optical Properties Investigation of Nanoporous Al2O3 Matrices with Embedded ADP and KB-5 Crystals // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. - P. 41.
  4. Shchur Ya., Kityk A.V., Adamiv V., Teslyuk I., Vitusevich S., Andrushchak A. Raman Spectroscopy and Symmetry Analysis in Structure Determining of Nanoconfined Nanocrystals // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. - P. 32.
  5. Bendak A., Senko I., Vynnyk D., Rubish V. Selenium thin Films Applications in THz Range // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. - P. 72.
  6. Danylov A., Venhryn B., Luniov S., Korolyshyn A., Senko I., Afanassyev D., Ratych A., Andrushchak A. Effect of Photogeneration on Concentration of Excess Carriers in Si and Ge Crystals // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. - P. 62.
  7. Danylov A., Vynnyk D., Haiduchok V. Optical Properties of Thin Film and Bulk Materials in the Visible and Infrared Spectrum Ranges // 3rd International Conference on Innovative Materials and Nanoengineering (IMNE'2023). Conference Program and Book of Abstracts. November 10-13, 2023. Dovgoluka, Ukraine. - P. 39.
  8. Bukliv R., Adamiv V., Bordun I., Andrushchak N., Teslyuk I., Andrushchak A. Analysis of some parameters of synthesized anodized aluminum oxide matrices // Conference Proceedings. 2024 IEEE 17th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering (TCSET) Lviv, Ukraine 08-12 October 2024. - P.359-363.
  9. Andrushchak N., Bukliv R., Venhryn B., Haiduchok V., Afanassyev D., Andrushchak Andrushchak N., Bukliv R., Venhryn B., Haiduchok V., Afanassyev D., Andrushchak A. Effect of chemical etching of mechanically treated monocrystalline germanium wafers on their modulation abilities in the sub-THz range // 4th International Conference on Innovative Materials and NanoEngineering (IMNE'2024). Conference Program and Book of Abstracts. September 13-16, 2024. Dovgoluka, Ukraine. - 4-10.
  10. Balaban O., Bukliv R., Danylov A., Sen'ko I., Venhryn B., Vynnyk D. Effect of Visible Range Radiation on Photomodulation of Subterahertz Radiation by Single Crystal Germanium // 4th International Conference on Innovative Materials and NanoEngineering (IMNE'2024). Conference Program and Book of Abstracts. September 13-16, 2024. Dovgoluka, Ukraine. - 2-6.
  11. Shchur Ya., Kityk A.V., Adamiv V., Vitusevich S., Andrushchak A. Experimental and Theoretical Investigations of Nanocomposite Materials Based on Si and SiO2 Porous Matrices // 4th International Conference on Innovative Materials and NanoEngineering (IMNE'2024). Conference Program and Book of Abstracts. September 13-16, 2024. Dovgoluka, Ukraine. - 2-2.
  12. Balaban O., Vynnyk D., Sen`ko I., Venhryn B., Danylov A., Andrushchak A. Analysis of Electrophysical Parameters of Semiconductors // 4th International Conference on Innovative Materials and NanoEngineering (IMNE'2024). Conference Program and Book of Abstracts. September 13-16, 2024. Dovgoluka, Ukraine. - 4-9.
  13. Venhryn B., Bukliv R., Danylov A., Haiduchok V., Senko I., Andrushchak A. The influence of etching processes of the surface of mechanically processed single-crystal germanium on the photomodulation of sub-terahertz radiation // VII International Scientific and Practical Conference "Solid State Physics and Chemistry: State, Achievements and Prospects", October 18-19, 2024, Lutsk. - p. 123. (in Ukrainian)
  14. Balaban O.V., Vinnyk D.M., Venhryn B.Ya., Danylov A.B., Andrushchak A.S. Electrically conductive properties of Si in the frequency range 10-2 - 106 Hz // XII International scientific conference. Relaxed, Nonlinear and Acoustic Optical Processes and Materials (RNAOPM'2024), Lutsk - Svityaz', 01 - 04.06.2024. - p.37. (in Ukrainian)
  15. Bukliv R. L., Balaban O. V., Venhryn B. Ya., Vynnyk D. M., Danylov A. B., Gaiduchok*** V., Andrushchak A. S. Surface preparation of germanium plates for use in subterahertz and terahertz radiation ranges // Lviv Chemical Readings - 2025: Collection of scientific papers of the XX Scientific Conference, Lviv, June 2-4, 2025. - 2025. - P. 118.16. (in Ukrainian)
  16. Balaban O., Bukliv R., Danylov A., Venhryn B., Vynnyk D., Andrushchak A. Electrophysical properties of Ge in the frequency range 10-1 - 105 Hz// Current problems of fundamental sciences: materials of the VI international scientific conference dedicated to the memory of Giordano Bruno, Lutsk, Svityaz, 09-12.06.2025. - 2025. - P. 16-17. (in Ukrainian)
  17. Bukliv R., Balaban O., Venhryn B., Vynnyk D., Danylov A. Effect of chemical etching on photoinduced modulation of subterahertz radiation by crystalline germanium // Chemical technology and engineering proceedings of the 5th International scientific conference, June 23-26th, 2025, Lviv, Ukraine. - 2025. - C. 204-208.
  18. D. Shulha, O. Buryy, V. Adamiv, A. Andrushchak. The photonic zone structures of arrays of KDP nanorods // International workshop for young scientists «Functional materials for technical and biomedical applications» (Lviv, October 14-16, 2025). - 2025. - P. 8.

Papers

As part of the completed project, the following scientific and technical articles were published:

  1. Shchur Ya., Andrushchak N., Kityk A.V., Andrushchak A. Lattice dynamics of Bi12GeO20 crystal: Polarized Raman scattering and first-principles analysis // Optical Materials. - 2024. - V.157(1). - 116078. https://doi.org/10.1016/j.optmat.2024.116078.
  2. Bendak A., Buryy O., Haiduchok V., Andrushchak A., Sahraoui B., Kityk A..Photo-induced switching for sub-terahertz applications // Optical Materials. -: 2026. - P. 117531.

Patents

The following documents were obtained as part of the completed project:

  1. Baluk V.I., Bendak A.V., Shulga D. O., Andrushchak A. S. Method of X-ray structural studies of porous silicon membranes filled with crystallites. Pat. 155881 (Ukraine), G01N23/20, Publ. 17.04.2024, Bull. No. 16/2024. https://sis.nipo.gov.ua/uk/search/detail/1795699/