Unlike metals, semiconductors increase their conductivity as you heat them (up to a point). Suggest an explanation.

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780134414232

검증된 단계별 안내

Step 1: Understand the basic structure of semiconductors. Semiconductors have a band structure with a valence band filled with electrons and a conduction band that is empty at absolute zero temperature.

Step 2: Recognize the role of thermal energy. As temperature increases, thermal energy excites electrons from the valence band to the conduction band.

Step 3: Explain the increase in charge carriers. The excitation of electrons creates electron-hole pairs, increasing the number of charge carriers available for conduction.

Step 4: Discuss the effect on conductivity. With more charge carriers (electrons and holes), the electrical conductivity of the semiconductor increases.

Step 5: Note the limitations. This increase in conductivity continues up to a certain temperature, beyond which other effects, such as lattice vibrations, may dominate and affect conductivity differently.

주요 개념

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Band Theory of Solids

Band theory explains the electronic structure of solids, distinguishing between conductors, insulators, and semiconductors. In semiconductors, the energy gap between the valence band and the conduction band is small, allowing electrons to jump into the conduction band when energy is supplied, such as through heat.

Temperature Dependence of Conductivity

In semiconductors, increasing temperature provides thermal energy that excites electrons from the valence band to the conduction band, enhancing conductivity. This contrasts with metals, where increased temperature causes increased lattice vibrations, impeding electron flow and reducing conductivity.

Intrinsic vs. Extrinsic Semiconductors

Intrinsic semiconductors are pure materials that conduct electricity due to thermally generated charge carriers, while extrinsic semiconductors have impurities added to enhance conductivity. The behavior of both types under temperature changes is crucial for understanding their conductivity variations with heat.