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The bandgap is a fundamental property of semiconductors and insulators, representing the energy difference between the valence band and the conduction band. It determines a material's electrical conductivity and is crucial in designing electronic and optoelectronic devices like transistors and solar cells.
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Concept
The valence band is the highest range of electron energy levels in a solid where electrons are normally present at absolute zero temperature. It plays a crucial role in determining the electrical conductivity of materials, as electrons must be excited to the conduction band to contribute to electrical conduction.
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The conduction band is the range of electron energy levels in a solid where electrons are free to move and contribute to electrical conductivity. In semiconductors and insulators, it is separated from the valence band by an energy gap, and electrons must gain sufficient energy to transition into it for conduction to occur.
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Semiconductors are materials with electrical conductivity between that of a conductor and an insulator, crucial for modern electronics. They are the foundation of integrated circuits and devices like transistors, enabling the miniaturization and performance enhancement of electronic technologies.
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Insulators are materials that resist the flow of electric current, making them essential for protecting and isolating electrical systems. They are characterized by their high resistivity and low conductivity, which prevent energy loss and ensure safety in electrical applications.
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Electronic band structure describes the range of energies that an electron within a solid may have and the range of energies that it may not have, crucial for understanding electrical conductivity and semiconductor behavior. It results from the periodic potential in a crystalline solid, leading to the formation of energy bands and band gaps, which determine the electronic properties of materials.
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The Fermi level is the energy level at which the probability of finding an electron is 50% at absolute zero temperature, serving as a reference point for electron energy distribution in solids. It plays a crucial role in determining the electrical properties of materials, influencing conductivity and behavior in semiconductors, metals, and insulators.
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A direct bandgap refers to the alignment of the conduction band minimum and the valence band maximum at the same momentum, allowing electrons to transition directly between these bands by emitting or absorbing a photon. This property makes materials with a direct bandgap highly efficient for optoelectronic applications like LEDs and laser diodes, as they facilitate strong light-matter interactions.
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The photovoltaic effect is the generation of voltage and electric current in a material upon exposure to light, forming the fundamental principle behind solar cells. This process involves the absorption of photons, which excites electrons, creating electron-hole pairs that are separated by an internal electric field to produce electricity.
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Quantum tunneling is a quantum mechanical phenomenon where particles pass through a potential energy barrier that they classically shouldn't be able to surmount. This process is crucial in various physical phenomena and technologies, including nuclear fusion in stars and the operation of tunnel diodes and scanning tunneling microscopes.
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The density of states (DOS) in physics and materials science quantifies the number of different states at a particular energy level that electrons are allowed to occupy in a system. It plays a critical role in determining the electronic properties of materials, influencing phenomena such as conductivity and band structure behavior.
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Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them, offering high efficiency, long lifespan, and low energy consumption compared to traditional lighting technologies. They are widely used in various applications, from display screens to general lighting, due to their versatility and environmental benefits.
A semiconductor temperature sensor is a device that uses semiconductor materials to measure temperature by exploiting the temperature-dependent properties of semiconductors. These sensors are widely used in various applications due to their high accuracy, linearity, and integration capability with electronic systems.
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Trap-assisted recombination is a process in semiconductors where charge carriers recombine through defect states or traps within the bandgap, which can significantly affect the efficiency of electronic and optoelectronic devices. This phenomenon is crucial in determining the performance of solar cells, LEDs, and other semiconductor devices, as it can lead to non-radiative losses and reduced carrier lifetimes.
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