arXiv subjects

Gil Atar

Publications and source records attributed to Gil Atar.

3 recordsLinked to original sources

arXiv2026

Strain-Enhanced Coherence in Curved hBN Quantum Emitters

Hexagonal boron nitride (hBN) hosts robust room-temperature single-photon emitters, yet their coherence is typically limited by phonon induced dephasing and spectral broadening. Here, we show that thermally induced curvature in bulk like hBN flakes provides a strain enabled route to suppress defect phonon coupling under ambient conditions. Nanoscale bubbles formed by thermal processing generate strong through thickness strain gradients, which we directly probe by infrared nano spectroscopy. These measurements reveal strain induced splitting of in-plane phonon modes, evidencing a substantial local modification of the phonon density of states. Quantum emitters localized within these curved regions exhibit markedly enhanced room temperature spectral purity, with Debye Waller factors of 0.91 and narrower line widths than emitters in flat regions. Photon correlation measurements confirm high-purity single photon emission at room temperature. Supported by first-principles calculations, we attribute this behavior to strain driven phonon redistribution, which depletes phonons in tensile regions and accumulates them in compressive regions, thereby creating locally phonon suppressed environments for defect emitters. These results establish strain engineering as an effective route for phonon control in hBN and open a pathway toward high coherence, room-temperature quantum light sources for integrated nano photonic platforms.

cond-mat.mtrl-sci↗

arXiv2025

Time Resolution Characterization of 4H-SiC LGADs with a ${}^{90}$Sr Source

This work presents timing measurements of 4H-SiC Low Gain Avalanche Detectors (4H-SiC LGADs) using beta particles from a ${}^{90}$Sr source. The 4H-SiC LGADs exhibit fast signal responses, and a time resolution of 61~ps was achieved, comparable to that of standard Si LGADs. The present limitation in the time resolution of 4H-SiC LGADs appears to stem from limited charge generation. Nevertheless, their higher voltage tolerance and faster carrier drift suggest that, with increased charge collection, their timing performance could approach or even surpass that of Si LGADs. These results demonstrate the strong potential of 4H-SiC LGADs as a robust platform for precision timing in future 4D tracking detectors, while also highlighting that signal charge is the dominant factor currently limiting their performance, indicating that further optimization of gain and drift structures will be essential for future development.

physics.ins-det↗

arXiv2025

Impact of Proton Irradiation on 4H-SiC Low Gain Avalanche Detectors (LGADs)

Silicon carbide (SiC) particle detectors have the potential to provide time resolutions and robust performance in extreme environments which exceed that of silicon detectors. In this work 4H-SiC low gain avalanche detectors (LGADs) and complementary PiN diodes were irradiated with 2.5 GeV protons at fluences up to 3.33$\times$10$^{14}$ p/cm$^2$. The electrostatic performance of both irradiated and non-irradiated devices was evaluated using current-voltage (I-V) and capacitance-voltage (C-V) measurements. Moreover, charge collection measurements using $\alpha$ particles were also conducted. SiC LGADs displayed a loss in rectification and gain with increasing proton fluence. Additionally, the reduction in capacitance and OFF-state current pointed to compensation of the gain layer as a gain reducing mechanism. The introduction of radiation induced defects also hinders carrier acceleration reducing impact ionization, leading to further gain reduction. However, despite the reduction in device performance, the demonstration of a measurable signal and gain after irradiation points to the potential of SiC LGAD detectors for future high energy physics applications.

physics.ins-det↗