What is the Difference Between Semiconductor and Metal?

The main difference between semiconductors and metals lies in their electrical conductivity and the way they respond to temperature changes. Here are the key differences between the two:

1. Electrical Conductivity: Metals have high electrical conductivity, meaning they can carry a large amount of electricity. In contrast, semiconductors have lower electrical conductivity, falling between conductors and insulators.
2. Temperature Dependence: The electrical conductivity of semiconductors increases rapidly with increasing temperature, whereas the electrical conductivity of metals decreases slowly with increasing temperature.
3. Doping: Semiconductors can be modified by doping, or introducing impurities, to change their electrical conductivity. This process can result in n-type semiconductors (with increased conductivity) or p-type semiconductors (with decreased conductivity). Metals do not have this property.
4. Bipolar vs. Unipolar: Semiconductors are bipolar, meaning they can conduct current through both electrons and positively charged holes. Metals, on the other hand, are unipolar conductors, with current carried solely by electrons.
5. Energy Bands: Metals have a Fermi energy located at the conduction band, where energy levels are smeared out. Semiconductors have a Fermi energy located at the bandgap, where energy states are more discrete. Insulators have a large bandgap, with all energy states below the Fermi energy occupied and all states above empty.

In summary, semiconductors have lower electrical conductivity than metals, a more rapid temperature dependency, and can be modified through doping. They are also bipolar conductors, while metals are unipolar. These differences in properties are due to the arrangement of energy levels in the material, known as energy bands.

Comparative Table: Semiconductor vs Metal

Here is a table summarizing the differences between semiconductors and metals:

In summary, the main differences between semiconductors and metals lie in their electrical conductivity, band structure, work function, and temperature dependence. Semiconductors have intermediate electrical conductivity, a Fermi level lying within the band gap, and work functions that can form different types of semiconductors based on electron affinity. In contrast, metals have high electrical conductivity, separate bands for occupied and unoccupied states, and a temperature-dependent electrical conductivity that remains relatively constant with temperature.