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Electronic Band Structure
Published in Joachim Piprek, Handbook of Optoelectronic Device Modeling and Simulation, 2017
Stefan Schulz, Eoin P. O'Reilly
As discussed in Section 1.1, the electronic band structure of semiconductor materials and their specific features are of central importance for determining their electronic and optical properties. This is not only of interest for a fundamental understanding of material properties; it also relates directly to their usefulness for devices such as transistors, lasers, or light-emitting diodes to name only a few. This has resulted in intense research efforts around the world to modify and tailor the electronic band structure of semiconductor materials, including the use of alloys, heterostructures, quantum confinement, and strain. Some of the most advanced devices now employ all of these techniques. Here, we focus our attention on some of the central features of the electronic band structure of bulk semiconductors.
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Published in Zbigniew Galazka, Transparent Semiconducting Oxides, 2020
The electronic band structure defines intrinsic electronic and optical properties of a material the knowledge of which enables to conclude a proper device design with desired functionality. Current computational power and advanced laboratory tools led to an explosion in studying material physics both theoretically and experimentally. Computational studies may provide hints to experimental research and explore structural, electronic, and optical properties, such as trapping effect, intrinsic defects, doping, conductivity type, energy gap and its nature, and optical transitions, as well as material limitations. On the other hand, experimental results in feedback may validate a mathematical model for electronic structure computation.
Neuroanatomy
Published in Richard Kerslake, Elizabeths Templeton, Lisanne Stock, Revision Guide for MRCPsych Paper A, 2018
The electronic band structure is known as a critical physical quantity in the condensed-matter physics that can provide full information on the electronic properties of materials. Energy gaps and energy dispersions are the main characteristics of electronic band structure to observe changes in electronic properties of various systems. The 1D band structure of pristine 7- and 6-ASiNRs are presented in Figures 5.2(a) and 5.2(b), respectively, in which the Fermi level (EF) is set at zero energy to measure all electronic states. The 1D energy bands fully belong to anti-crossing weak dispersed bands, and the 1D valence and conduction bands are symmetric via Fermi level at low-lying energy that becomes asymmetric at deeper energies. This comes from the weak separation of π and σ bonds in low-buckled Si-Si bonds, in which π bands of Si-3pz orbitals mainly dominate at low-lying energy, while the σ bands of Si-(3px, 3py) orbitals fully contribute at deep energy. The pristine ASiNRs show a direct energy gap (Egd) that is determined by the highest occupied valence and lowest unoccupied conduction band at Г point. The band gap strongly depends on the widths of ASiNRs that are governed by the rule of Eg(2n+1) > Eg(2n) > Eg(2n + 2), where n is an integer. With n = 3, the widths of the studying systems are 7-ASiNR and 6-ASiNR, in which the band gap of the former is much larger than the latter as shown in Table 5.2. This rule remains unchanged for other widths. The rich 1D band structure of ASiNRs will be dramatically diversified under various halogen adsorptions.
Green synthesis of CuNb2O6 thin film using allium cepa as catalyst
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Emeka Charles Nwanna, Patrick Ehi Imoisili, Sarah Bitire, Tien-Chien Jen
Traditionally, determining the optical band gap (Eg) necessitates the development of a thin film material’s electronic band structure. The optical band gaps (Eg) of the formed Nb2O5 and CuNb2O6 thin films were evaluated by determining the absorption spectra of the films via the UV–visible absorption spectroscopy. Thereafter, the optical band gap was retrieved from the resultant tauc plot as shown in Figure 7. A tauc plot is typically represented by the quantity (hν) (photon energy) along the abscissa, versus the quantity (αhν)2 represented along the ordinate. The direct bandgap is calculated using the relationship of the photon energy and absorption coefficient α in equation 5.
Structural stability of SrZrO3 perovskite and improvement in electronic and optical properties by Ca and Ba doping for optoelectronic applications: a DFT approach
Published in Philosophical Magazine, 2019
S. S. A. Gillani, Riaz Ahmad, I. Zeba, Muhammad Rizwan, Muhammad Rafique, M. Shakil, Saqib Jabbar, M. Siddique
From the electronic band structure, we can define two regions/bands of energy which are separated by a gap, which is not occupied by the electrons, and is called the materials band gap. The energy bands below and above the fermi level are the Valence band (VB) and the conduction band (CB), respectively. Generally, the separation between maxima of VB and minima of CB minimum is a band gap. The possible movements of electrons from VB maximum to CB minimum are characterised by the band structure profile.