Resistance of one cube centimeter of germanium at 18°C equals 72 Ohm. At 19°C it decreases until 68 Ohm. Such significant resistance changes while insignificant variation of temperature is typical for semiconductors. While temperature grows the resistance usually falls. It may be strongly changed by radiation, mechanical deformations etc.
When an element of 5th group is added, the electron conductivity type (n-type) may be obtained. In such way antimony doped germanium (SbGe) is prepared. Element of 3rd group doping results to hole conductivity type or p-type, as it happens in gallium doped germanium hole-type system. These features are in the basis of producing of various semiconductors, such as transistors, diodes, and rectifiers applied in various modern electronic devices.
Germanium is applied in such fields of modern technology as low temperature thermometers, infrared detectors etc.
All these applications require extra-pure germanium, in which impurities concentration does not exceed 10-7%). It minimizes crystal structure defects as dislocations etc. Single crystals are grown for achieving this goal. |