Integrated microsystem for blue/UV detection

A fully integrated sensor microsystem for blue/ultraviolet (UV) radiation d etection is presented. The photosensitive part includes a 1-mm(2) blue/UV-s elective stripe-shaped photodiode, which has maximal response in the short- wavelength range. A 15-times smaller infrared (IR) photodiode is added to c ompensate the parasitic photocurrent generated by the blue/UV photodiode in the IR range. Thus, a very high ratio of the responsivities at 420 nm and 1 mu m of 1500 is achieved. A transimpedance amplifier with 1 G Omega feedb ack resistor followed by an inverter is integrated on the same silicon chip . The main features of the operational amplifier (op amp) are a low offset (< 0.5 mV) and fail-safe operation. This sensor has a maximal responsivity of 150 mV/nW at lambda = 420 nm, corresponding to 44% quantum efficiency. T he system has a noise equivalent power of 5 x 10(-13) W. The 2.2 mm(2) micr osystem is realized in a standard CMOS 0.5 mu m process without any post-pr ocessing step. (C) 2000 Elsevier Science S.A. All rights reserved.