A semiconductor material’s electrical conductivity is somewhere between that of a conductor, such as metallic copper, and that of an insulator, such as glass. As the temperature rises, its resistivity reduces, whereas metals have the opposite effect. The conductivity of a crystal structure can be modified in a favorable way by introducing impurities (doping) to it. When two separate doped regions in the same crystal exist, a semiconductor junction is generated. The behavior of charge carriers such as electrons, ions, and electron holes at these...