TEMPERATURE AND INFRARED QUENCHING OF EQUILIBRIUM CONDUCTIVITY IN CdSexs1-x FILM Valijon T. Mirzaev, Bozorboy J. Akhmadaliyev, Iftikhorjon I. Yulchiev, Muminjon M. Madraximov, Tokhirbek I. Rakhmonov East European Journal of Physics, 2025 A method for obtaining CdSe, CdSexS1-x films with high photosensitivity has been developed. This method involves thermal treatment of freshly prepared films in vacuum and air in a specially prepared quasi-hermetic chamber in the presence of CdCl2 or CuCl2, which ensures uniform diffusion of sensitizing substances. Experiments have shown that CdSe, CdSexS1-x films with stable and reproducible electrophysical properties are obtained by heating at the following temperatures: in air in the presence of CdCl2 – 470℃; in the presence of CuCl2 – 300℃; in vacuum – 480℃. Temperature and infrared quenching of equilibrium conductivity are observed only in optimally photosensitive samples with both fast (r) and slow (s) recombination centers and efficiently operating intercrystalline barriers. However, various external influences significantly affect the carrier motion, leading to the loss of high photosensitivity of the sample. Infrared quenching of equilibrium conductivity is observed at T < 300K and low infrared light intensities IIR < 10-1 lx in the entrance spectral absorption range of 1.0 ÷ 3.0 μm, and a pronounced photoconductivity with a clearly defined entrance is observed at IIR ≥ 10-1 lx.
Enhanced optoelectronic properties of ZnO thin films through boron and fluorine Co-doping F. T. Yusupov, V. T. Mirzaev, T. I. Rakhmonov, O. R. Nurmatov, D. Sh. Khidirov, et al. Journal of Ovonic Research, 2025 This research investigates how co-doping zinc oxide (ZnO) thin films with boron (B) and fluorine (F) affects their structural, electrical, and optical properties Leveraging a chemical solution deposition technique and advanced characterization methods, the research investigates the synergistic impact of simultaneous doping with boron (B) and fluorine (F) on enhancing ZnO’s performance for optoelectronic applications. X-ray diffraction (XRD) analysis revealed significant lattice distortions, reduced crystallite sizes, and improved crystallinity with increasing dopant concentrations. Scanning electron microscopy (SEM) images demonstrated reduced grain sizes and increased surface roughness, correlating with enhanced morphological properties. Photoluminescence (PL) spectroscopy highlighted shifts in emission peaks and increased radiative recombination efficiency, indicating modifications to defect states and band structure. Hall effect measurements confirmed improvements in carrier concentration, mobility, and overall electrical conductivity, peaking at optimized doping levels. The obtained results demonstrate that ZnO thin films co-doped with boron (B) and fluorine (F) exhibit significant potential for utilization in advanced optoelectronic technologies, particularly in light-emitting diodes, photodetectors, and solar cell devices. The systematic approach provides valuable insights into doping-induced property modifications, offering a robust framework for tailoring ZnO-based semiconductors for specific applications.
Bio-engineered ZnO/PSi nanocomposites: structural and optical properties for biosensing applications Tokhir Rakhmonov, Fakhriddin Yusupov, Valijon Mirzaev, Ikhtiyorjon Tursunov, Jakhongir Rakhimjonov, et al. Bio Web of Conferences, 2025 Porous silicon (PSi) and zinc oxide (ZnO) nanocomposites have emerged as promising materials for optoelectronic, sensing, and biomedical applications due to their unique structural and optical properties. This study investigates the synthesis, structural characterization, and photonic response of ZnO/PSi nanocomposites fabricated via atomic layer deposition (ALD). The influence of ZnO deposition on the optical properties of PSi is analyzed using UV-Vis absorption, photoluminescence (PL), and X-ray diffraction (XRD) techniques. Post-deposition annealing enhances the crystallinity and charge transport dynamics of ZnO, optimizing its performance for photonic applications. Additionally, the biocompatibility of the ZnO/PSi system is evaluated through cytotoxicity assays, highlighting its potential for biomedical use. The findings of this research provide valuable insights into the design and optimization of ZnO/PSi-based materials for advanced photonic and biosensing applications.
Photocunductivity spectra of thin solid solution films CdSexS1-x Bozorboy Akhmadaliyev, Tokhirbek Rakhmonov, Khusanboy Sulaimonov, Ozodbek Nurmatov E3s Web of Conferences, 2024 This paper presents the results of a study on the energy spectra of activation of intrinsic defects in photosensitive films of solid solution CdSexS1-x depending on the conditions of their preparation and thermal treatment in different environments. This study investigates the photoconductivity spectra of thin films composed of the solid solution CdSexS1-x, focusing on the impact of preparation and thermal treatment conditions on the activation energy spectra of intrinsic defects. The films were synthesized using thermal evaporation in a vacuum and subjected to various thermal processes. The results indicate that the photoconductive properties are highly influenced by structural defects and point defects within the crystalline lattice, which create deep levels in the forbidden zone of the semiconductor. These findings advance the understanding of the physical processes in polycrystalline films and highlight the potential of CdSexS1-x films for developing light-emitting diodes and lasers in the infrared and visible spectra.
NANOCRYSTALLINE ZnO FILMS ON VARIOUS SUBSTRATES: A STUDY ON THEIR STRUCTURAL, OPTICAL, AND ELECTRICAL CHARACTERISTICS Numonjon A. Sultanov, Zokirjon X. Mirzajonov, Fakhriddin T. Yusupov, Tokhirbek I. Rakhmonov East European Journal of Physics, 2024 Zinc oxide (ZnO), characterized by its wide bandgap and substantial exciton binding energy, is extensively utilized in optoelectronic applications, including blue and ultraviolet light-emitting diodes (LEDs) and lasers. In this study, the deposition of ZnO films on various substrates (Si, sapphire, GaAs, GaP) through thermal oxidation is investigated as a cost-effective alternative to molecular beam epitaxy (MBE) and chemical vapor deposition (CVD). A thorough analysis of the structural, optical, and electrical properties of these films is presented, with a focus on their suitability for heterojunction diodes. The methodology employed involved the thermal evaporation of Zn films in a vacuum chamber, followed by oxidation in a pure oxygen atmosphere. The conditions for deposition were optimized to yield nanocrystalline ZnO films with a preferential orientation, as confirmed by X-ray diffraction (XRD) analysis. An increase in the optical bandgap was indicated by optical transmittance measurements, while photoluminescence (PL) spectra exhibited uniform and enhanced crystalline integrity across the samples. The electrical characterization of ZnO-based heterojunction diodes on different substrates revealed distinct electrical characteristics, with variations in leakage current and ideality factor observed. The specific resistances of the Zinc Oxide (ZnO) films were determined by analyzing the linear portions of the current-voltage (I-V) curves.
ENHANCING ZnO/Si HETEROJUNCTION SOLAR CELLS: A COMBINED EXPERIMENTAL AND SIMULATION APPROACH1 Fakhriddin T. Yusupov, Tokhirbek I. Rakhmonov, Mekhriddin F. Akhmadjonov, Muminjon M. Madrahimov, Sherzod Sh. Abdullayev East European Journal of Physics, 2024 In this study, we explore the fabrication and optimization of ZnO/Si heterojunction solar cells to enhance their performance through precise control of electron affinity and bandgap properties. ZnO thin films were synthesized using thermal oxidation in a high-vacuum chamber, followed by annealing to improve crystallinity and electrical characteristics. The photovoltaic performance of the ZnO/Si heterojunction solar cells was systematically characterized, and Quantum ESPRESSO simulations were employed to refine the electronic properties of ZnO. Our results show significant improvements in open-circuit voltage, short-circuit current density, and overall conversion efficiency. The optimization of ZnO/Si heterojunction solar cells involves enhancing the electronic properties of ZnO thin films. Quantum ESPRESSO simulations were utilized to optimize the ZnO structure, calculate the band structure and density of states (DOS), and study the effects of Ga and Mg doping on the electronic properties of ZnO. The initial step in our study involved the structural optimization of ZnO to determine its lowest energy configuration. The optimization of the band offset engineering to improve the efficiency of n-ZnO/p-Si photovoltaic cells was found to be critical. Doping ZnO with Ga and Mg improved the band alignment with Si, reduced recombination losses, and enhanced charge carrier mobility. Our findings underscore the potential of optimized ZnO/Si heterojunction solar cells for high-efficiency solar energy conversion, demonstrating their viability as cost-effective and efficient solutions for renewable energy applications. This study highlights the importance of precise material engineering and simulation-driven optimization in developing advanced photovoltaic devices.
