Germanium

Germanium is used in specialised electronic, optical and technological applications. Its semiconductor properties allow it to be incorporated into certain electronic devices, while its refraction index and behaviour against infrared radiation make it valuable for manufacturing optical components. It is also used in some high-performance solar cells and in materials for optical fibre. Although silicon dominates much of conventional electronics, germanium remains important when its specific properties offer technological advantages.

Germanium and silicon are semiconductors of the same group of the periodic table, but they have different electronic properties. Germanium has a narrower bandgap, which modifies its electrical and optical response, especially at room temperature. This can favour certain high-speed or detection applications, although it can also increase unwanted currents in certain devices. Silicon, on the other hand, offers advantages of cost, technological availability and the formation of a very useful oxide for manufacturing integrated circuits.

Germanium can act as a semiconductor material in specialised solar cells, especially in multijunction devices used in space applications. These cells combine several semiconductor layers that absorb different regions of the solar spectrum, making better use of the light energy than a conventional unit. Germanium can serve as a substrate and participate in the structure of certain cells. Its choice depends on factors such as performance, weight, cost and expected operating conditions of the photovoltaic system.

Yes. Highly pure germanium is used in semiconductor detectors capable of measuring the energy of gamma radiation with excellent energy resolution. When radiation interacts with the material, it generates electric charges whose signal allows estimating the deposited energy. These detectors are used in nuclear research, material analysis and specialised environmental measurements. For proper operation, many systems of highly pure germanium require refrigeration, which reduces electrical noise and improves the quality of recorded signals.

Germanium presents high transmission of certain infrared wavelengths, especially in regions used for obtaining thermal images. For this reason, it is used in lenses, windows and other optical components of infrared cameras and thermal vision systems. Its high refraction index also influences lens design. However, its transmission depends on the wavelength, purity and surface treatment, so it is not suitable for any optical application.

In the manufacture of certain optical fibres, small amounts of germanium are incorporated into silica to modify its refraction index. This variation allows creating a central region through which light is guided along the fibre. Control of composition and refraction index profile is essential to obtain the desired optical properties. Thanks to this technique, fibres can transport light signals over great distances and form part of modern telecommunications infrastructures.

Germanium is a semiconductor with a relatively narrow bandgap and carrier mobility that can be favourable in certain devices. These characteristics allow studying and developing electronic components that take advantage of its response to electric fields and high-frequency signals. However, its behaviour also depends on temperature, impurities and crystal defects. Therefore, although it offers advantages in some specialised applications, it does not automatically replace silicon, whose properties and manufacturing processes are optimised for a huge variety of circuits.