arXiv subjects

Jan Koloros

Publications and source records attributed to Jan Koloros.

3 recordsLinked to original sources

arXiv2026

Low-resistivity nitrogen-doped p-type Cu2O thin films enabled by millisecond flash lamp annealing

Flash lamp annealing (FLA) provides millisecond-scale thermal processing, but its effects on p-type Cu2O and nitrogen-related defects remain poorly understood. Reactively sputtered Cu2O:N films with different nitrogen content were deposited using reactive high-power impulse magnetron sputtering and exposed to a single 1.9 ms FLA pulse at 4.9 - 11.7 J cm-2. Their compositional,morphological, structural, vibrational, electrical, and optical responses were evaluated. WDS showed no statistically significant change in total elemental composition, and XRD confirmed retention of cubic Cu2O. Nitrogen-containing films exhibited surface coarsening, shifts of the Cu2O reflections, and non-monotonic changes in the Raman band assigned to molecular N2. Nitrogen incorporation substantially reduced the as-deposited resistivity. The very low value of 0.045 {\Omega}cm was obtained after FLA at 4.9 J cm-2, whereas higher energy densities markedly increased resistivity. Hall measurements showed increasing mobility but decreasing hole concentration. At high energy densities, the optical band gap of nitrogen-rich films widened. The results define a narrow low-energy processing window with a positive effect on electrical properties, whereas high-energy FLA modifies the structure and optical absorption edge but degrades electrical conductivity.

cond-mat.mtrl-sci↗

arXiv2026

Crystalline b-Ga2O3 thin films deposited via reactive magnetron sputtering of a liquid Ga target

Ga2O3 thin films were deposited by reactive magnetron sputtering from a liquid gallium target. The influence of deposition temperature, substrate type, and discharge parameters on the structural and electrical properties was systematically investigated. Films deposited on silicon and quartz glass exhibit polycrystalline growth, whereas sapphire substrates enable highly oriented growth of b-Ga2O3 with a preferred (-201) orientation. The lowest electrical resistivity of 7x10_3 ohm.cm was obtained for films deposited on sapphire at a temperature of 585C. At this temperature, the films reach sufficient crystalline quality to enable efficient charge carrier transport and thus the manifestation of unintentional conductivity. At higher deposition temperatures, pronounced crystallization occurs; however, it is not homogeneous throughout the entire film thickness, which leads to a deterioration of the electrical properties. These results demonstrate that, despite intrinsic limitations, reactive magnetron sputtering can be successfully employed for the preparation of Ga2O3 thin films with optimized electrical properties when appropriate substrates and deposition temperatures are selected.

cond-mat.mtrl-sci↗

arXiv2025

Ultra-low-resistivity nitrogen-doped p-type Cu2O thin films fabricated by reactive HiPIMS

We have successfully fabricated the nitrogen-doped cuprous oxide thin films on the amorphous standard soda-lime glass by reactive high-power impulse magnetron sputtering. The energy of film-forming particles was controlled by the value of pulse-averaged target power density, which has a significant impact on the elemental composition, structure and optoelectrical properties of the films. We have shown that the high-energy regime is more suitable for preserving Cu2O structure and leads to continuous substitution of oxygen by nitrogen compared with the low-energy regime. Moreover, in the high-energy regime, it is possible, to some extent, to independently control the electrical resistivity and optical properties. The electrical resistivity decreases down to 5 x10-2 ohm.cm at the optical band gap 2.0-2.3 eV. Special attention is paid to the formation of nitrogen molecules and their ability to form shallow acceptor states. Experimental results supported by our DFT calculations indicate that N2 replacing Cu in the Cu2O lattice is one possible (but not the only possible) acceptor. We have also found that the formation of nitrogen molecules is preferred in a high-energy regime.

cond-mat.mtrl-sci↗