arXiv subjects

Bogdan Dryzhakov

Publications and source records attributed to Bogdan Dryzhakov.

5 recordsLinked to original sources

arXiv2026

Foundry CMOS platform for multimodal quantum materials characterization

Quantum materials experiments increasingly rely on microwave, electrical, thermal, optical, and structural probes, but these capabilities are typically assembled from custom hardware that limits reproducibility and scalability. Here we show that a commercial 65-nm CMOS process can be repurposed as a passive, foundry-manufacturable characterization platform by functionally partitioning its metal stack into microwave, thermal, and electrical subsystems within a 1 mm2 footprint. The integrated RF architecture enables cryogenic magnetic susceptibility measurements of Fe3GeTe2 heterostructures at 1.75 K without sample-specific fabrication. We further demonstrate NV-center optically detected magnetic resonance (ODMR) with >20% contrast at 4-9 dBm microwave power, reducing power requirements by 20-25 dB relative to conventional antenna-based approaches while maintaining sensitivities of 2-3 uT/sqrt(Hz). We additionally confirm compatibility with in-situ electron-beam imaging, showing no measurable degradation in image quality upon device operation. These results establish a scalable, foundry-manufacturable platform for multimodal quantum sensing and materials characterization.

cond-mat.mtrl-sci↗

arXiv2025

Probing the Nanoscale Excitonic Landscape and Quantum Confinement of Excitons in Gated Monolayer Semiconductors

Engineering and probing excitonic properties at the nanoscale remains a central challenge in quantum photonics and optoelectronics. While exciton confinement via electrical control and strain engineering has been demonstrated in 2D semiconductors, substantial nanoscale heterogeneity limits the scalability of 2D quantum photonic device architectures. In this work, we use cathodoluminescence spectroscopy to probe the excitonic landscape of monolayer $WS_2$ under electrostatic gating. Exploiting the high spatial resolution of the converged electron beam, we resolve a homojunction arising between gated and ungated regions. Moreover, we reveal an exciton confinement channel arising from an unconventional doping mechanism driven by the interplay between the electron beam and the applied gate fields. These findings offer new insights into the optoelectronic behavior of monolayer semiconductors under the combined influence of electron-beam excitation and electrostatic gating. Our approach provides a pathway for exciton manipulation at the nanoscale and opens opportunities for controlling quantum-confined exciton transport in two-dimensional materials.

cond-mat.mes-hall↗

arXiv2025

Nitrogen Vacancies Induce Fatigue in Ferroelectric $\mathrm{Al_{0.93}B_{0.07}N}$

Wurtzite ferroelectrics (e.g., $\mathrm{Al_{0.93}B_{0.07}N}$) are being explored for high-temperature and emerging near-, or in-compute, memory architectures due to the material advantages offered by their large remanent polarization and robust chemical stability. Despite these advantages, current $\mathrm{Al_{0.93}B_{0.07}N}$ devices do not have sufficient endurance lifetime to meet roadmap targets. To identify the defects responsible for this limited endurance, a combination of electronic measurements and optical spectroscopies characterized the evolution of defect states within $\mathrm{Al_{0.93}B_{0.07}N}$ with cycling. Ultrathin ($\sim$10 nm) metal contacts were used to optically probe regions subject to ferroelectric switching; photoluminescence spectroscopy identified the emergence of a transition near 2.1 eV whose intensity scaled with the non-switching polarization quantified via positive-up negative-down (PUND) measurements. Accompanying thermally stimulated depolarization current (TSDC) and modulus spectroscopy measurements also observed the strengthening of a state near 2.1 eV. The origin of this feature is ascribed to transitions between a nitrogen vacancy and another defect deeper in the bandgap. Recognizing that the impurity concentration is largely fixed, strengthening of this transition indicates an increase in the number of nitrogen vacancies. Switching, therefore, creates vacancies in $\mathrm{Al_{0.93}B_{0.07}N}$ likely due to hot-atom damage induced by the aggressive fields necessary to switch wurtzite materials that ultimately limits endurance.

cond-mat.mtrl-sci↗

arXiv2025

Defect Engineering in Large-Scale CVD-Grown Hexagonal Boron Nitride: Formation, Spectroscopy, and Spin Relaxation Dynamics

Recently, numerous techniques have been reported for generating optically active defects in exfoliated hexagonal boron nitride (hBN), which hold transformative potential for quantum photonic devices. However, achieving on-demand generation of desirable defect types in scalable hBN films remains a significant challenge. Here, we demonstrate that formation of negative boron vacancy defects, VB-, in suspended, large-area CVD-grown hBN is strongly dependent on the type of bombarding particles (ions, neutrons, and electrons) and irradiation conditions. In contrast to suspended hBN, defect formation in substrate-supported hBN is more complex due to the uncontrollable generation of secondary particles from the substrate, and the outcome strongly depends on the thickness of the hBN. We identify different defect types by correlating spectroscopic and optically detected magnetic resonance features, distinguishing boron vacancies (formed by light ions and neutrons) from other optically active defects emitting at 650 nm assigned to anti-site nitrogen vacancy (NBVN) and reveal the presence of additional dark paramagnetic defects that influence spin-lattice relaxation time (T1) and zero-field splitting parameters, all of which strongly depend on the defect density. These results underscore the potential for precisely engineered defect formation in large-scale CVD-grown hBN, paving the way for the scalable fabrication of quantum photonic devices.

cond-mat.mtrl-sci↗

arXiv2019

Deciphering the Effect of Traps on Electronic Charge Transport Properties of Methylammonium Lead Tribromide

Organometallic halide perovskites (OMHPs) have undergone remarkable developments as highly efficient optoelectronic materials for a variety of applications. Several studies indicated the critical role of defects on the performance of OMHP devices. Yet, the parameters of defects and their interplay with free charge carriers remain unclear. In this study we explore the dynamics of free holes in methylammonium lead tribromide (MAPbBr3) single crystals using the time of flight (ToF) current spectroscopy. By combining the current waveform (CWF) ToF spectroscopy and the Monte Carlo (MC) simulation, three energy states were detected in the band gap of MAPbBr3. Additionally, we found the trapping and detrapping rates of free holes ranging from a few us to hundreds of us and, contrary to previous studies, a strong detrapping activity was revealed. It was shown that these traps have a significant impact on the transport properties of MAPbBr3 single crystal devices, including drift mobility and mobility-lifetime product. To demonstrate the impact of traps on the delay of free carriers, we developed a new model of the effective mobility valid for the case of multiple traps in a semiconductor. Our results provide a new insight on charge transport properties of OMHP semiconductors, which is required for further development of this class of optoelectronic devices.

cond-mat.mtrl-sci↗