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Fundamentals of Nanoscale Electronic Devices
Published in Khurshed Ahmad Shah, Farooq Ahmad Khanday, Nanoscale Electronic Devices and Their Applications, 2020
Khurshed Ahmad Shah, Farooq Ahmad Khanday
In this chapter, we have explained the basic physics and features involved in the operation of these nanoscale electronic devices. The free electron model is successful in explaining many properties of metals, such as thermal conductivities, thermionic emission, and thermoelectric effect. However, this model fails to explain the properties of solids that are determined based on their internal structure. Quantum mechanics provides a clear picture of the nature at the subatomic scale and predicts all phenomena in terms of probabilities. The important thing to note here is that the mass of a nanomaterial is very small; therefore, the gravitational forces are negligible and electromagnetic forces are dominant in determining the behavior of atoms and molecules in these materials [6,7]. Furthermore, the quantum theory is used to explain their structure and properties, which contradict the results of the classical theory. Also, one important characteristic of materials that are being used for electronic devices is the origin of energy bands, as different solids possess different band structures, which give rise to a wide range of their electrical properties [8]. Depending on the nature of band occupation by electrons and the width of forbidden energy bands, all solids can be classified into conductors, semiconductors, and insulators. On the basis of these characteristics, the materials are used in different types of electronic devices for different applications.
Solids
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Neil Allan, Elaine A. Moore, Lesley E. Smart
A metal has a partially filled band, called the conduction band, with no energy gap above the highest-occupied level. Electrons near this highest-occupied level are readily promoted into the empty orbitals in the band when an electric field is applied, and this gives rise to the high electrical conductivity of the metals. As in the free-electron model, the highest-occupied level in the metal at 0 K is the Fermi level.
Matter
Published in Mohammad E. Khosroshahi, Applications of Biophotonics and Nanobiomaterials in Biomedical Engineering, 2017
In solid-state physics, the free electron model is a simple model for the behaviour of valence electrons in a crystal structure of a metallic solid. It was developed by Sommerfeld, who combined the classical Drude model with quantum mechanical Fermi–Dirac statistics and hence, it is also known as the Drude–Sommerfeld model. The free electron is successful in explaining a number of experimental phenomena, namely:the Wiedemann–Franz law which relates electrical conductivity and thermal conductivitythermal electron emission and field electron emissionthe temperature dependence of the heat capacitythe shape of the electronic density of statesthe range of binding energy valueselectrical conductivities
The impact of hydrogen on mechanical performance of carbon alloy plates detected by eddy current method
Published in Nondestructive Testing and Evaluation, 2023
Haiting Zhou, Huandong Huang, Dongdong Ye, Qiang Wang, Chenxi Zhu
Electromagnetic properties such as resistivity and permeability are inherent properties of materials. Electromagnetic properties are related to grain size, grain orientation, influence of inclusions, chemical composition, and thickness of magnetic materials. The main factors affecting the electrical conductivity of materials are temperature, stress, cold working, crystal defects, heat treatment and geometric size effects. According to the free electron model [23], the resistivity of conductive materials is related to the effective mass of electrons, electron concentration and the dominant scattering mechanism. The dominant scattering mechanism is affected by sample composition, structure, temperature, inclusions and strain.