arXiv subjects

Afreen Anamul Haque

Publications and source records attributed to Afreen Anamul Haque.

3 recordsLinked to original sources

arXiv2026

Phonon-Assisted Photoluminescence and Ultrafast Exciton Dynamics in Two-Dimensional Silicon Carbide

Phonon assisted photoluminescence provides a direct window into exciton phonon interactions in semiconductors. Using fully ab initio many-body perturbation theory, including finite momentum Bethe Salpeter calculations, we investigate phonon-assisted emission and exciton dynamics in two dimensional (2D) hexagonal silicon carbide (hSiC) and benchmark its response against 2D h boron nitride (hBN). By explicitly resolving exciton phonon matrix elements, we identify an electron-phonon scattering channel mediated by A$^\prime$ high energy longitudinal and transverse optical phonons as the dominant contributors to sideband formation and quantify their spectral weights. We find that h SiC exhibits pronounced phonon-assisted sidebands comparable to hBN, despite a smaller exciton phonon energy separation and fewer resolved replicas. The bright \textbf{K}\textbf{K} exciton governs near UV zero phonon emission, while intervalley excitons acquire radiative character through symmetry allowed optical phonon coupling. Temperature dependent scattering rates reveal an ultrashort bright exciton lifetime of approximately 300 fs at 10 K, highlighting rapid exciton relaxation driven by intrinsic phonon channels.

cond-mat.str-el↗

arXiv2026

Transition-Metal Tailored $Ga_{2}O_{2}$ Monolayer: From Room-Temperature Gas Sensing to Chemical Scavenging

Pristine $Ga_{2}O_{2}$ monolayers suffer from poor sensitivity and weak molecular capture, limiting their application in toxic gas detection and environmental detoxification. Here, we employ first-principles density functional theory (DFT) calculations to investigate the gas sensing and scavenging properties of $Ga_{2}O_{2}$ monolayers substitutionally tailored via seven transition-metals (TM): Pd, Zn, Zr, Mo, Ag, Ti, and Pt. All TM-substituted monolayers exhibit negative formation and binding energies, negligible lattice distortion, and structural stability in molecular dynamics simulations. Performance evaluation against eight toxic industrial and three environmental gases reveals functionalities ranging from selective, reusable room-temperature sensing to permanent molecular capture. Ag substitution exhibits exceptional selectivity for $NO$ with moderate adsorption strength (~-0.83eV), an up to eight-order-of-magnitude conductivity enhancement, besides facilitating reusable $O_2$ and $NO_2$ detection. Additionally, Pd-, Zn-, Zr-, and Mo substitutions tune selectivity toward $NO$, $NO_2$, $CO_2$, $CO$, and $O_2$. Coming to applications towards toxic gas capture, Zr- and Mo-substituted systems selectively scavenge oxidizing gases, whereas Ti and Pt act as universal scavengers. Further analysis reveals that Pd- and Ag-substituted monolayers remain selective for $NO$, while Zn substitution favors $NO_2$ detection even in ambient atmospheric conditions. Thus, these tailored $Ga_{2}O_{2}$ monolayers offer a practical platform for atmospheric monitoring and detoxification.

cond-mat.mtrl-sci↗

arXiv2025

Gas Sensing Properties of Novel Indium Oxide Monolayer: A First-Principles Study

We present a comprehensive first-principles investigation into the gas sensing capabilities of a novel two-dimensional Indium Oxide (In2O3) monolayer, using density functional theory (DFT) calculations. Targeting both resistive-type and work function based detection mechanisms, we evaluate interactions with ten hazardous gases (NH3, NO, NO2, SO2, CS2, H2S, HCN, CCl2O, CH2O, CO) as well as ambient molecules (O2, CO2, H2O). The monolayer shows pronounced sensitivity towards NO and H2S, and work function modulation enables detection of NH3 and HCN. Mechanical strain further broadens detection capability, enhancing adsorption and selectivity. These results establish 2D In2O3 as a tunable platform for next-generation miniaturized gas sensors for environmental monitoring and safety applications.

cond-mat.mtrl-sci↗