What are the 'free' carriers in the different electronic...

Name: Problem 2, Chapter 6: Solar Energy: The Physics and Engineering of Photovoltaic Conversion, Technologies and Systems
Uploaded: 2021-09-08T14:53:52-08:00
Duration: 1 min 35 s
Channel: Ajay Singhal
Description: What are the 'free' carriers in the different electronic bands of a semiconductor? (a) Electrons in conduction band and holes in valence band. (b) Holes in conduction band and electrons in valence band. (c) Both electrons and holes in conduction band when an electric field is applied. (d) Both electrons and holes in valence band when an electric field is applied.

What are the 'free' carriers in the different electronic bands of a semiconductor? (a) Electrons in conduction band and holes in valence band. (b) Holes in conduction band and electrons in valence band. (c) Both electrons and holes in conduction band when an electric field is applied. (d) Both electrons and holes in valence band when an electric field is applied.

What are the 'free' carriers in the different electronic bands of a semiconductor?
(a) Electrons in conduction band and holes in valence band.
(b) Holes in conduction band and electrons in valence band.
(c) Both electrons and holes in conduction band when an electric field is applied.
(d) Both electrons and holes in valence band when an electric field is applied.

Key Concepts

Semiconductor Band Structure

The semiconductor band structure refers to the energy levels available to electrons in a semiconductor material, primarily divided into the valence band and the conduction band. The valence band is typically filled with electrons, while the conduction band is higher in energy and, when occupied by electrons, allows them to move freely, leading to electrical conduction.

Conduction Band

The conduction band is the energy band in a semiconductor where electrons gain sufficient energy to be free from the influence of individual atoms and can move throughout the material, thus contributing to electrical current flow.

Valence Band

The valence band is the energy band in a semiconductor that is usually filled with electrons under equilibrium conditions. When electrons leave this band, they create vacancies known as holes, which can move and serve as positive charge carriers.

Electrons

Electrons are negatively charged particles that, when excited into the conduction band of a semiconductor, become mobile charge carriers capable of moving freely under the influence of an electric field, thereby contributing to electrical conduction.

Holes

Holes are the absence of electrons in the valence band of a semiconductor and act as positive charge carriers. When an electron is excited from the valence band to the conduction band, the resulting hole can move through the lattice and participate in conduction.

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