High-Sensitivity CMOS-Integrated Floating Gate-Based UVC Sensors

We report on novel UVC sensors based on the floating gate (FG) discharge principle. The device operation is similar to that of EPROM non-volatile memories UV erasure, but the sensitivity to ultraviolet light is strongly increased by using single polysilicon devices of special design with low FG capacitance and long gate periphery (grilled cells). The devices were integrated without additional masks into a standard CMOS process flow featuring a UV-transparent back end. Low-cost integrated UVC solar blind sensors were optimized for implementation in UVC sterilization systems, where they provided feedback on the radiation dose sufficient for disinfection. Doses of similar to 10 mu J/cm(2) at 220 nm could be measured in less than a second. The device can be reprogrammed up to 10,000 times and used to control similar to 10-50 mJ/cm(2) UVC radiation doses typically employed for surface or air disinfection. Demonstrators of integrated solutions comprising UV sources, sensors, logics, and communication means were fabricated. Compared with the existing silicon-based UVC sensing devices, no degradation effects that limit the targeted applications were observed. Other applications of the developed sensors, such as UVC imaging, are also discussed.

Automated summary

We introduce novel UVC sensors based on the floating gate discharge principle, which exhibit enhanced sensitivity to ultraviolet light through a special design featuring low FG capacitance and long gate periphery. These low-cost integrated sensors are optimized for use in UVC sterilization systems, providing feedback on the radiation dose required for disinfection. The sensors can be reprogrammed up to 10,000 times and accurately measure UVC radiation doses typically employed for surface or air disinfection.