arXiv subjects

Pavel Baroch

Publications and source records attributed to Pavel Baroch.

6 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 Ωcm 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

Bias Tunable Transport Modulation and Gas Selectivity in Layered BiOI: A DFT NEGF Study

Understanding the interplay between adsorption energetics and charge-transport modulation is essential for the rational design of low-power and bias-tunable gas sensors. Here, we present a comprehensive first-principles study of gas selectivity in layered bismuth oxyiodide (BiOI) by integrating density functional theory with nonequilibrium Green's function transport calculations. The adsorption and bias-dependent transport responses toward NO2, NH3, CO2, and representative volatile organic compounds are systematically examined. While NH3 and NO2 exhibit strong chemisorption and localized electronic perturbations, CO2 interacts through weak physisorption, demonstrating that adsorption strength alone does not determine sensing performance. Instead, the evolution of transmission channels near the Fermi level governs the sensing response. Bias-dependent calculations reveal an electrically tunable sensitivity hierarchy, in which weakly adsorbed CO2 preserves conductive pathways and exhibits pronounced low-bias sensitivity despite minimal charge transfer. Recovery-time analysis further highlights the trade-off between transport modulation and reversibility for strongly adsorbed species. These results establish a transport-centered selectivity framework for layered BiOI and provide mechanistic insight into electric-field-controlled gas sensing under ambient conditions.

cond-mat.mtrl-sci↗

arXiv2026

Boron-assisted stabilization of low-resistivity mixed-valence Cu-O thin films prepared by reactive magnetron sputtering

This study systematically investigated the influence of boron incorporation in Cu-O thin films and the effect of oxygen partial pressure ($p_{\rm ox}$) on the phase evolution, chemical bonding, and electrical characteristics of the prepared films. A phase transition from Cu$_2$O to Cu$_2$O/Cu$_4$O$_3$ to CuO was observed as oxygen partial pressure increased. Boron incorporation significantly broadened the stability window of the Cu$_2$O and Cu$_4$O$_3$ phases and delayed the transition to CuO at higher oxygen partial pressure. In the highly B-doped Cu-O films, Cu$_4$O$_3$ was stabilized even under oxygen-rich conditions along with the CuO phase, suggesting that boron significantly altered the oxidation pathway. The formation of B-O and possible B-O-Cu configurations altered the local oxygen chemistry and promoted mixed-valence copper oxide phases. Electrical measurements revealed that highly B-doped Cu-O films exhibited a delayed transition from a high-resistivity low-$p_{\rm ox}$ regime to a low-resistivity mixed-valence regime, ultimately reaching approximately 0.06 $Ω$ cm, among the lowest reported resistivities for a CuO-like material. These findings demonstrate that boron doping is an effective approach for tailoring the phase stability, defect chemistry, and electrical characteristics of Cu-O thin films for optoelectronic and photovoltaic applications.

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↗

arXiv2024

Enhancement of hole mobility in high-rate reactively sputtered Cu2O thin films induced by laser thermal annealing

In presented work, a reactive high-power impulse magnetron sputtering (r-HiPIMS) was used for high-rate deposition ( 170 nm/min) of Cu2O films. Films were deposited on a standard soda-lime glass (SLG) substrate at a temperature of 190C. As-deposited films exhibit poor hole mobility in the orders of 1 cm2/Vs. We have systematically studied the effect of laser thermal annealing (LTA) procedure performed using high-power infrared laser under different laser parameters (number of pulses, length of the pulse). We have found, LTA procedure could significantly enhance the hole mobility (up to 24 cm2/Vs in our case). We have also fitted the results of a temperature-dependent Hall measurement to clarify the mechanism of the reported increase in hole mobility. Moreover, we have discussed the effect of the LTA procedure on microstructure (crystallinity, surface morphology) and on the value of optical band gap.

physics.app-ph↗