Topic:

Glossary: G

Here you are going to find explications of important terms in plasma technology:

I,J

P,Q

X,Y,Z

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gallium arsenide (GaAs): The binary compound gallium arsenide (GaAs, gallium + arsenic) is a semiconductor that can be semi conductive (endowed with elements of the groups II, IV, or VI of the periodic system) as well as semi isolating (non-endowed). Components made of gallium arsenide connect ten times faster than their comparable pendants made from silicon; in addition, they are less interference-prone with analog signals and consume less energy. Therefore, gallium arsenide is supposed to be an important basic material in telecommunications. In high-capacity mobile phones, the components for reception and transmission of signals (integrated circuits) are based on gallium arsenide.
Besides, gallium arsenide is used for transmitting information through glass fibre nets via lasers or surface-emitting lasers (VCSEL), as well as to supply satellites with energy from highly sophisticated solar cells (photovoltaics). In fundamental research and the semiconductor industry, particularly the material system AlGaAs/GaAs (aluminium gallium arsenide / gallium arsenide) is used for the production of semiconductor hetero-structures. The disposal of electronic components causes big problems because of the toxic component arsenic in gallium arsenide.
gas discharge: Through connection to an electric charge, electrons can be generated in gases. Depending on the gas, the strength of the vacuum, connected voltage/frequency, very intense luminous phenomena can result.
GDOS: Glow Discharge Optical Spectroscopy, a surface analysis method for thick layers. The sample is made to the cathode in a direct-current plasma, and is herewith vaporised step by step. Impacts between the vaporised particles and the atoms of the plasma gas (Ar) result in the characteristic emission of the evaporated atoms of the layer.
generator: Electric power supply for ignition and firing of a plasma (AC, DC).
GHz plasma system: see „microwave plasma“
glass: Amorphously solidified material
glass fibre: If melted glass is pulled apart under defined thermodynamic conditions and forces, then long fibres are produced. Glass fibres are mainly used to conduct light. A fibre optic cable is structured such that a cylindrical glass fibre is wrapped by a medium with a lower refractive index, and a protective covering. At the interface between the two transparent media with different refractive indexes, the light is reflected almost loss-free (total reflectance). In comparison with usual copper cables, glass fibres have the advantage of a wider band-width so that they conduct signals faster and with less losses. The elasticity modulus of glass fibres differs only marginally from the one of the compact material glass. The glass fibres have an amorphous structure and therefore isotropic mechanical properties. They behave ideally elastic until fracture. Furthermore, their material damping is slender.
Glass fibres are employed in construction materials as well. E.g. they are added to concrete where they serve as reinforcement. Glass fibre reinforced concrete is applied with currogated plates, cladding plates or lost formwork. Also, glass fibres are employed in screed. Besides, fine concrete is reinforced by glass fibre textiles, then called textile reinforced concrete. In aeronautics and space engineering, as well as in automobile engineering, glass fibres are of big importance. In aeronautics and space engineering, mainly supporting elements are built of long glass fibres. In the automobile industry, long glass fibres are mainly used for the reinforcement of thermoplastic elements (e.g. coverings) at the moment, the trend going towards supporting components, though.
In process engineering, glass fibres are especially applied in wound tubes. Here, they feature by their good durability against media and their electric isolation properties. In electrical engineering, glass fibres are particularly used as reinforcement fibres in blanks or in or in electromagnetic transparent coverings. And in high-voltage engineering, it is made use of the high strength and the isolation properties of these fibres in isolators. In order to improve subsequent treatment, glass-fibre reinforced plastics can be pre-treated by a plasma such that fibres are uncovered
glow discharge: A glow phenomenon induced on metal surfaces caused through electron bombardment.
gluing Teflon: see „etching Teflon“
graft polymerisation: Polymerisation onto an already built polymer material, mostly yielding a new side-chain of the already existing polymer. Graft polymerisations can also be executed via plasma, by first plasma-treating a substrate so that surface-radicals are generated, and afterwards (mostly without plasma) feeding monomers that are networkable through radicals; those form new polymer chains, starting from the radicals' positions. The switch-on and and -off of the plasma can as well be realised in the form of a pulsed plasma.