germanium (Ge)
Germanium is a chemical element. It belongs to the main group IV in the periodic table and has the atomic number 32. Germanium is a semiconductor with semi-metallic properties, whose conductivity changes strongly with temperature or doping. Like other semiconductors, it is used in monocrystalline form in microelectronics components.
Germanium atoms have four electrons in the valence band, which are connected to those of the neighboring atoms. If an electron is torn out of the electron bond by energy input, it can be used for charge transport and leaves a hole at its former position.
The charge transport can be increased by additional electrons released and by additional electrons added. These additional electrons are inserted by selective impurity, doping. Germanium has a band gap of 0.7 electron volts( eV). This value corresponds to the energetic gap between the valence band and the conduction band of germanium.
Like silicon, germanium is used in semiconductor devices, but it is much more temperature-dependent than silicon.