Nanostructured absorption and emission layers for thermal infrared detectors and emitters

• Applicant: Professor Dr.-Ing. Gerald Gerlach
• Subject Area: Microsystems
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267557604

Fast thermal infrared detectors with high detectivity must show a sufficiently high thermal insulation to ambient as well as a low thermal mass (heat capacity). It is possible to manufacture very thin detector elements having a thickness of less than 1 µm. However, absorption layers or stacked layer systems are required to ensure high absorptivity, which leads to thick layers with disadvantageous high heat capacities and poor heat conduction. Preliminary tests showed that very thin layers manufactured with glancing angle deposition (GLAD) provide a good refractive index matching between air and sensitive material and, therefore, combine a high absorptivity with a very low layer thickness. The properties of the layer can be specifically influenced by variation of the deposition angle allowing the manufacturing of layers with high and broadband absorption behavior. At the same time these absorption layers can be used as electrodes in pyroelectric sensors. All those relationships should be modelled and experimentally investigated and should lead to design guidelines, which can be used to derive process parameters of the GLAD-technology from given technical requirements.The layers described above can also be used as thermal emitters. However, it has to be stable at very high temperatures, because the radiated power increases with operating temperature. Therefore, an investigation of the GLAD-technology for high-temperature materials and integration in silicon technology should be carried out in the second part of the project. Such ultra-thin radiant heaters with very low heat capacity are more efficient, i.e. have a lower electrical power consumption, than state of the art heaters and can be operated at higher frequencies. This would lead to tremendous advantages for many applications and is to be proven on demonstrators.

• DFG Programme: Research Grants
• Major Instrumentation: Elektronenstrahlverdampfer
• Instrumentation Group: 8380 Schichtdickenmeßgeräte, Verdampfungs- und Steuergeräte (für Vakuumbedampfung, außer 833)