Optics and electronics

The deposition and functionalization of ultra thin layers play a key role in a multiplicity of applications in optics and electronics. Examples in the field of optics are:

• X-ray mirrors, which consist of multiple nanometer thick layers

• antireflection coatings and scratch resistant layers for plastic optics, e.g. eyeglass lenses or displays

• transparent insulating layers for window panes (low emission layers), which almost completely prevent thermal emission losses from window surfaces

In optoelectronics a multiplicity of new components like organic light emitting diodes (OLED) or semiconductor diode lasers are based on na-nostructured layer systems (see chapter 5.4). Sensors and actuators in microelectronic applications often require the integration of the sensor and actuator materials into the components by means of coating processes such as PVD, CVD, or sol gel techniques. Here also ISAM (Ionic Self Assembled Monolayers) are important, showing functional characteristics, e.g. electrical conductivity, optical, piezoelectric or photovoltaic properties, which are selectively adjustable by chemical modification. Such applications are important for components such as silicon circuits, micromechanical and microfluidic systems as well as SAW elements.

As nanotechnological components with importance for space applications in particular SAW elements should be mentioned, which are used in satellite telecommunications. Here the transition to ever higher frequencies requires a structuring of the associated SAW elements in the nanometer range. For example communication systems with working frequencies from 10 to 15 GHz require lateral structures from 50 to 100 nm and a layer thickness from 10 to 30 nm for the respective SAW elements.44 Further nanotechnologically influenced electronical high speed components are HEMT (High Electron Mobility Transistor) and HBT (Hetero-junction Bipolar Transistor), which already found entrance into industrial mass production as fast variants of bipolar and field-effect transistors. These transistors possess an outstanding signal-to-noise ratio in microwave receivers and transmitters for the application in modern radar and communication systems. Here in particular components on the basis of WBG (Wide Band Gap) semiconductors such as SiC or GaN will gain significance in the future. These materials allow increased operating voltages, higher power densities, better signal-to-noise ratios and thus smaller and more efficient components with lower requirements concerning cooling systems, which is important especially in the context of the miniaturization of satellite systems.

A further interesting application of nanolayers are transparent coatings on the basis of nanotubes developed in a SBIR project of NASA, which can be manufactured by means of sol gel procedures. Through the dispersion of the nanotubes in the polymer matrix a high electrical conductivity of the composites is obtained, which might be interesting for application as anti-static coatings in space structures and components as well as electrode materials for solar cells.

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