Which of the following is NOT a characteristic of a semiconductor?

A semiconductor is a material that has electrical conductivity between that of a conductor and an insulator. One of the key characteristics of semiconductors is that they do conduct electricity, but not as well as metals (which are good conductors). They can be manipulated to control their conductive properties through processes such as doping, which involves adding impurities to alter their conductivity.

Another important aspect of semiconductors is that they exhibit high resistance in their pure form but can become conductive under certain conditions, particularly when temperature increases or when they are doped with certain elements. This temperature dependence means that as the temperature rises, the conductivity of a semiconductor typically increases due to the enhanced movement of charge carriers.

The option stating that semiconductors are "always a good conductor" is incorrect because it contradicts the fundamental nature of semiconductors. While they can conduct electricity, they do not do so at the same level as metals and do not have the same characteristics inherent to good conductors like copper or aluminum. Therefore, labeling a semiconductor as always a good conductor fails to recognize the specific and variable conditions affecting its conduction properties.