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Technological challenges >> Electronics and microelectronics - Optoelectronics
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Study of EBIC and cathodoluminescence applied to narrow gap photodiodes for cooled IR détection

Département d'Optronique (LETI)

Laboratoire d'Imagerie IR



Since 40 years, CEA LETI is developing IR detection technologies using narrow gap semi-conductors. This led to the creation of the Lynred Company, formerly Known as Sofradir, now leader in the IR imaging market. In the frame of the collaborative work we have with Lynred for the development of new generations of IR imager, new characterisation needs appear. It addresses different issues, starting from the fine understanding of the photodiode operation when reducing its pixel pitch. It also addresses the understanding of the effects of the metallurgical and technological induced defects on the final IR detection performances. The proposal here is to study the behaviour of narrow gap IR photodiodes when excited with an electron beam within a scanning electron microscope (SEM). A mapping of the electron beam induced current (EBIC) brings important information about charge transport in the narrow gap, whereas the mapping of the associated induced IR luminescence (cathodo-luminescence) carries further and complementary information about radiative recombination of injected charges. This information is particularly interesting when interaction with defects occurs in the structure. In our characterisation group, the EBIC experiment is now operational at cryogenic temperatures. On the other hand, the cathodo-luminescence part of the experiment has to be developed to complete EBIC images. Once operational, the full picture EBIC+cathodo should be investigated using different samples from our fabrication line, focusing on small pixel pitches and high operation temperature structures, making the connection with all the other electro-optical characterisation benches available in our lab.

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