arXiv subjects

Cyprian Mieszczynski

Publications and source records attributed to Cyprian Mieszczynski.

6 recordsLinked to original sources

arXiv2026

Structural and Optical Characteristics of $β-Ga_2O_3$ Implanted with Rare Earth Ions

We investigated the structural evolution and optical properties of $β-Ga_2O_3$ crystals implanted with different rare-earth (RE) ions using channeling Rutherford Backscattering Spectrometry, Positron Annihilation, Photoluminescence, and Photoluminescence Excitation spectroscopies. The studies reveal that implantation-induced disorder, accompanying phase transitions, and post-annealing structural recovery are largely insensitive to the implanted RE species. The defect microstructure is also found to be similar for all implanted RE ions. Thermal annealing does not completely remove radiation-induced defects but instead drives their rearrangement into larger defect complexes. Unimplanted (virgin) $β-Ga_2O_3$ exhibits strong UV-visible emission attributed to oxygen vacancies, whereas the introduction of RE ions produces additional emission lines originating from electronic transitions within RE3+ ions. The results indicate that RE3+ ions are excited through the host conduction band, followed by non-radiative relaxation to the 4f excited states and radiative decay to the respective ground states. Fluence-dependent studies of Yb3+ reveal the onset of concentration quenching, while RE-related emission remains efficient even in the presence of substantial lattice disorder. These findings provide new insight into defect evolution in ion-implanted beta-Ga2O3 and clarify the excitation mechanisms of RE3+ ions, offering guidance for optimizing the optical performance of $β-Ga_2O_3$:RE materials.

cond-mat.mtrl-sci↗

arXiv2026

From phase transformation to amorphization: damage accumulation in Yb-implanted $β-Ga_2O_3$

This study provides a comprehensive analysis of the radiation response and structural evolution of differently oriented$β-Ga_2O_3$ single crystals subjected to Yb ion implantation over a wide fluence range from $5 \times 10^{12}$ to $1 \times 10^{16}$~cm$^{-2}$ ($0.04$--$74$~dpa). A multi-technique approach (RBS/c, PAS, HRTEM, and HRXRD) was employed to investigate the mechanisms of damage accumulation. The results reveal a multi-stage process of defect evolution. At a critical threshold of around $0.4$~dpa, the accumulation of lattice strain triggers a phase transformation from monoclinic $β$-Ga$_{2}$O$_{3}$ to a defective spinel structure of $γ$-Ga$_{2}$O$_{3}$. Notably, the formation of this new phase is accompanied by strain relaxation. With further irradiation, defects develop within the crystal structure of $γ$-Ga$_{2}$O$_{3}$. The associated atomic reorganization at this stage is reflected by a distinct dip in the damage accumulation curve and the appearance of stacking faults in the subsurface region of the implanted layer. In contrast to previous reports suggesting high radiation stability of this phase, the present study clearly demonstrates that continuous defect accumulation results in a significant increase in both displaced atoms and vacancy-type defects, with a strong depth dependence in their type and density. Ultimately, at an irradiation level of approximately $7$~dpa, the surface layer amorphizes. With further irradiation, the amorphous layer expands, gradually replacing the transient $γ$-Ga$_{2}$O$_{3}$ phase. These findings reveal that the radiation tolerance of gallium oxide is highly sensitive to ion-specific interactions and strain-induced instabilities, thereby challenging the previously assumed robustness of this material under high-fluence ion irradiation.

cond-mat.mtrl-sci↗

arXiv2026

Comprehensive structural and optical analysis of differently oriented Yb-implanted $β$-Ga$_2$O$_3$

This study presents investigations of Yb-doped $β$-Ga$_2$O$_3$, an ultrawide bandgap semiconductor with potential use in future power and optoelectronic devices operating in high-radiation environments. The research has focused on the problem of structural damage caused by the implantation of Yb-ions into three differently oriented crystals and the optical response of created systems. The (001), (010), and (-201)-oriented $β$-Ga$_2$O$_3$ crystals were implanted with three different fluences of 150 keV Yb ions and examined using a variety of experimental techniques: high-resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry in channeling mode (RBS/c), Raman and photoluminescence (PL) spectroscopies, to provide comprehensive information about studied systems. Furthermore, the RBS/c studies were supported by Monte Carlo simulations. The results show distinctions between differently oriented crystals. In particular, (010)-oriented crystals are characterized by the lowest concentration of extended defects and the presence of compressive stress. In contrast, samples with the other two orientations exhibit tensile stress and significantly higher levels of extended defects. Interestingly, the PL spectra of (010)-oriented $β$-Ga$_2$O$_3$ show the lowest emission from Yb$^{3+}$ ions, suggesting that specific types of extended defects, whose formation is more favorable in the other two orientations than in (010), enhance Yb$^{3+}$ luminescence instead of suppressing it.

cond-mat.mtrl-sci↗

arXiv2026

Application of dual-tree complex wavelet transform for spectra background reduction

This paper presents a method for background removal in experimental data processing using the Dual-Tree Complex Wavelet Transform (DTCWT). The technique is based on discrete wavelet theory (DWT) and addresses limitations of commonly used numerical approaches, such as fitting or filtering methods. Compared with Fourier-transform-based techniques, DTCWT provides improved performance for signal extraction. The proposed method is universal and enables analysis of arbitrary data ranges without restrictions on their position in time. It satisfies key requirements of signal analysis, including signal preservation and reduction of processing bias. An algorithm for background reduction is implemented to extract and enhance meaningful spectral information. The approach is demonstrated on two different types of spectra: X-ray powder diffraction and photoluminescence measured for the $β-Ga_{2}O_{3}$ crystal. Practical aspects of DWT-based processing are also discussed, including the selection of wavelet families and decomposition levels. The method is available as a software package for spectral background reduction.

cond-mat.mtrl-sci↗

arXiv2026

Energy-Dependent Dechanneling in Cu: Insights from Monte Carlo Channeling Simulations

Ion channeling and backscattering techniques are powerful tools for studying crystal lattice disorders and defect structures in crystalline materials. However, the accurate interpretation of channeling phenomena necessitates the utilization of simulation models that account for the intricate interactions between point defects, dislocations, and extended defect clusters. The present paper introduces a Monte Carlo method that reproduces experimental spectra over a wide range of analyzing beam energies and enables quantitative identification of defect types and distributions. The simulations reveal characteristic energy dependencies that distinguish point defects from extended defects, offering a novel perspective on disturbances caused, for example, by ion implantation in metals and semiconductors. To this end, the McChasy code has been developed as a flexible and accessible tool for scientists, enabling the modeling of various crystal systems, including complex semiconductors, multilayer epitaxial films, and oxide crystals. The program's integration of experimental data on ion channeling with defect modeling establishes a robust framework for defect analysis in materials science. The present article expounds upon the simulation capabilities of the program by reproducing the characteristic "elbows" in channeling spectra that were previously observed in experiments conducted on Cu crystals.

cond-mat.mtrl-sci↗

arXiv2025

Defect Accumulation in beta-Ga2O3 Implanted with Yb

Radiation-induced crystal lattice damage and its recovery in wide bandgap oxides, in particular beta-gallium oxide (beta-Ga2O3), is a complex process. This paper presents the first study on the process of the defects accumulation in beta-Ga2O3 implanted with Rare Earth (RE) ions and the impact of Rapid Thermal Annealing (RTA) on the defects formed. (-201) oriented beta-Ga2O3 single crystals were implanted with Yb ions fluences ranging from 1 x 1012 to 5 x 1015 at/cm2. Channeling Rutherford Backscattering Spectrometry (RBS/c) was used to study the crystal lattice damage induced by ion implantation and the level of structure recovery after annealing. The quantitative and qualitative analyses of collected spectra were performed by computer simulations. The resulting accumulation curve reveals a two-step damage process. In the first stage, the damage of the beta-Ga2O3 is inconspicuous, but begins to grow rapidly from the fluence of 1 x 1013 at/cm2, reaching the saturation at the random level for the Yb ion fluence of 1 x 1014 at/cm2. Further irradiation causes the damage peak to become bimodal, indicating that at least two new defect forms develop for the higher ion fluence. These two damage zones differently react to annealing, suggesting that they could origin from two phases, the amorphization phase and the new crystalline phase of Ga2O3.

cond-mat.mtrl-sci↗