We present a theoretical study on the interaction between high-intensity electric fields and quantum well width modulation in an asymmetric GaAsSb/GaAs Morse quantum well. The gradual change in antimony concentration creates a position-dependent effective mass and highly asymmetric potential. Solving the effective mass Schro & uml;dinger equation with the finite-element method shows that narrower wells produce blue shifts and stronger confinement of heavy-hole wavefunctions. Under strong electric fields, bound states evolve into quasi-bound resonances, the enabling calculation of tunneling rates and carrier lifetimes. The Stark effect reveals asymmetry: positive fields shift energy levels downward, while negative fields enhance localization and strengthen both linear and third-order nonlinear optical responses. Combined control of well width and electric field allows precise tuning of energy spectra, tunneling dynamics, and optical nonlinearities. These findings provide insights for designing field-tunable optoelectronic devices and highlight the promise of asymmetric Morse quantum wells for enhanced performance under reverse-bias conditions.
We investigate the emergence and manipulation of topological phases in monolayer jacutingaite Pt2HgSe3 by modeling its low-energy electronic structure with an effective Kane-Mele Hamiltonian subjected to electrostatic gating and time-periodic irradiation. This material provides an ideal platform for such a study, as its large intrinsic spin-orbit coupling (SOC) stabilizes a robust quantum spin Hall phase with an experimentally accessible bulk gap. Rather than relying on momentum-resolved probes or explicit edge-state calculations, we demonstrate that the topological nature of the system can be inferred entirely from the structure of the electronic density of states (DOS), focusing on the number, separation, and magnitude of spectral discontinuities. These discontinuities arise from band extrema and gap openings induced by SOC and light-driven band renormalization. In particular, a quantum spin Hall phase is characterized by fewer than two closely spaced steps in the DOS, while the absence of any pronounced features near the chemical potential signals a semimetallic regime. The appearance of two well-separated discontinuities marks a fully gapped phase, which may correspond either to a trivial band insulator or to a quantum Hall insulator; these two cases are unambiguously distinguished by the relative heights of the DOS steps, reflecting their underlying band degeneracies. By establishing a direct correspondence between topological phases and simple, experimentally measurable DOS features, our work provides a transparent and broadly applicable framework for identifying topological order in driven two-dimensional materials without requiring edge-sensitive measurements.
Based on the recent synthesis of two-dimensional (2D) 1T-phase GeO2, the piezoelectric and thermoelectric properties of a Janus GeSO monolayer were systematically investigated using first-principles calculations. Compared to its 1T-GeO2 counterpart, the GeSO monolayer exhibits a direct band gap of 1.476 eV, distinct Raman spectrum, strong visible-light optical absorption, pronounced in-plane and out-of-plane piezoelectric response, and a small exciton binding energy. Owing to its small effective mass and deformation potential, the electron mobility is significantly higher than the hole mobility. Furthermore, the presence of heavy sulfur atoms in the asymmetric Janus structure suppresses phonon group velocity while enhancing anharmonic scattering, leading to a low thermal conductivity of 2.92 W/mK. At 550 K and under an achievable electron concentration of 2.46 & times;1013 cm-2, a notable n-type thermoelectric figure of merit (ZT) of 0.52 is obtained. These results demonstrate the promising potential of the Janus GeSO monolayer for applications in piezoelectric and low-temperature thermoelectric devices.
SF6 decomposition gas sensors are key devices for detecting the insulation status of electrical equipment. This manuscript proposes using Cun, Pdn, and Rhn(n = 1-3) clusters modified HfSe2 monolayers to detect three SF6 decomposition gases (SO2, SOF2, and SO2F2). To study the application of metal cluster-doped two-dimensional nanomaterials in gas sensors, density functional theory (DFT) calculations are used to investigate their adsorption properties, sensitivity, and electronic behavior. The adsorption mechanisms and electronic properties of target gases on the modified substrates are systematically studied through DFT analysis of adsorption energy, density of states, and deformation charge density. The results show that TMnclusters enhance the reactivity of HfSe2 surfaces, leading to varying improvements in conductivity and adsorption capacity. The research results confirm the applicability of Cun-, Pdn-, and Rhn-doped HfSe2 monolayers for detecting SF6 decomposition gases. This analysis is of great significance for exploring the application of HfSe2-based gas sensors as SF6 decomposition gas detectors in the insulation monitoring of electrical equipment.
Water adsorption at metal interfaces influences elementary steps in corrosion, electrocatalysis, and heterogeneous catalysis under aqueous or humid conditions. In this work, H2O adsorption on the (100) and (110) surfaces of Co, Ni, Pd, and Pt is studied using spin-polarized density functional theory within the PAW-PBE framework. Adsorption energies, optimized geometries, metal-oxygen distances, and spin-resolved d-band centers are analyzed to assess the influence of metal type, surface orientation, and spin polarization. The results show that spin polarization significantly stabilizes adsorption on magnetic 3d metals, revealing the limitations of the classical d-band center model for spin-polarized surfaces. An extended description using two spin-resolved d-band centers, epsilon up arrow d and epsilon down arrow d, is required to capture the observed trends. Co(100) and Co(110) exhibit the strongest water binding, while Pt surfaces show the weakest adsorption. A clear correlation is found between the position of the d-band center and adsorption strength, and the on-top site is identified as the most favorable adsorption configuration.
