What characterizes an extrinsic semiconductor in terms of doping?

An extrinsic semiconductor is specifically characterized by the intentional introduction of impurities, or dopants, which alter its electrical properties. In the case of extrinsic semiconductors, the doping process is used to create either p-type or n-type charge carriers, depending on the type of dopant introduced.

When a semiconductor material, typically silicon, is doped with elements that have fewer valence electrons (like phosphorus or arsenic), it introduces extra electrons, resulting in n-type conductivity. Conversely, doping with elements that have more valence electrons (like boron) creates "holes," leading to p-type conductivity. This targeted doping is crucial because it allows for precise control over the conductivity and behavior of the semiconductor, which is essential for designing and fabricating a variety of electronic components such as diodes and transistors.

The other options presented do not capture the essential characteristic of an extrinsic semiconductor effectively. While mixing with multiple impurities can happen, it is not a defining feature. The mention of different doping elements for different regions refers more to device structure rather than the fundamental characteristics of extrinsic semiconductors. Lastly, stating that an extrinsic semiconductor remains neutral in charge balance is misleading because the purpose of doping is to create an imbalance that facilitates conductivity