Band gap

About: Band gap is a research topic. Over the lifetime, 86889 publications have been published within this topic receiving 2242479 citations. The topic is also known as: bandgap & forbidden band.

Pressure dependence of the electronic properties of cubic III-V In compounds.

Abstract: Electronic and ground-state properties of the binary In compounds in the zinc-blende structure are reported. They are evaluated in the local-density approximation using norm-conserving nonlocal pseudopotentials. Besides the lattice constant, the bulk modulus, and its first and second pressure derivative, the first- and second-order pressure coefficients of the main band gaps (at \ensuremath{\Gamma}, X, and L) are given. The hydrostatic deformation potentials and the crossover pressure from direct to indirect band gap are presented and compared with recent experimental values.

A facile solution approach to W,N co-doped TiO2 nanobelt thin films with high photocatalytic activity

Abstract: Hydrogen titanate nanobelt thin films were fabricated by oxidizing Ti plates with H2O2 solutions containing H2WO4 and C3H6N6 at 80 °C. A subsequent calcination achieved W,N co-doped TiO2 nanobelts, which possessed a band gap of 2.3 eV and high photocatalytic activity under both UV and visible light illumination.

Alpha Lead Oxide (α-PbO): A New 2D Material with Visible Light Sensitivity

Abstract: Even though transition metal dichalcogenides (TMDCs) are deemed to be novel photonic and optoelectronic 2D materials, the visible band gap being often limited to monolayer, hampers their potential in niche applications due to fabrication challenges. Uncontrollable defects and degraded functionalities at elevated temperature and under extreme environments further restrict their prospects. To address such limitations, the discovery of a new 2D material, α-PbO is reported. Micromechanical as well as sonochemical exfoliation of 2D atomic sheets of α-PbO are demonstrated and its optical behavior is investigated. Spectroscopic investigations indicate layer dependent band gaps. In particular, even multilayered PbO sheets exhibit visible band gap > 2 eV (direct) which is rare among semiconducting 2D materials. The emission lifetime of multilayer PbO atomic sheets is 7 ns (dim light) as compared to the monolayer which gives 2.5 ns lifetime and an intense light. Density functional theory calculations of layer dependent band structure of α-PbO matches well with experimental results. Experimental findings suggest that PbO atomic sheets exhibit hydrophobic nature, thermal robustness, microwave stability, anti-corrosive behaviour and acid resistance. This new low-cost, abundant and robust 2D material is expected to find many applications in the fields of electronics, optoelectronics, sensors, photocatalysis and energy storage.

Observation of large quadratic electro-optic effect in GaAs/AlGaAs multiple quantum wells

Abstract: We simultaneously measure the intensity modulation level and the optical spectrum of the output of a multiple quantum well modulator, and use these data to deduce the electro‐optic coefficients. The effect is quadratic, with a measured ‖s33‖=4.6×10−13 cm2/V2 at a wavelength 12 meV below the band gap. This is approximately 800 times the coefficient measured further from the band gap. We are able to achieve a fractional change in the refractive index of 3.7%. Despite the size of this effect, when we operate the device as an intensity modulator, we observe a linewidth enhancement factor of α=1.0, which means the chirp induced in the device’s output will be small.