Ultraviolet Si photodetectors
We investigate silicon detectors of ultraviolet radiation which are insensitive to visible and infrared radiation (solar blind). Silicon is technologically and financially convenient for detector material, however its sensitivity maximum is in the visible and near infrared part of the spectrum, where sun radiation is several orders of magnitude stronger than UV radiation. Solar blind detectors are of interest for burners in industrial plants, but also for the protection against harmful effects of UV radiation.
In CMT we considered two designs of UV chips. One of them utilizes bulk micromachining in KOG to form a micrometer-thin diaphragm in a silicon-on-oxide wafer. The other uses standard silicon PIN photodiodes with a shallow junction and makes use of downconversion from UV to visible by fluorescent material. The key part of the device is a proprietary metal-dielectric filter that cuts off visible and IR radiation, suppressing them for at least 4-6 orders of magnitude. The latter solution offers a potential to fabricate very inexpensive silicon UV diodes convenient for mass production and compatible with the standard silicon technologies.