Design and testing of a CMOS BDJ detector for integrated micro-analysis systems
This paper reports the design and testing of a CMOS BDJ (Buried Double pn Junction) detector for developing integrated microanalysis systems. The device is an optical detector producing two photocurrents (I1 and I2) when it receives an incident flux. It can be operated either as a photodetector by using its output current I1+I2, or as a colour detector if the photocurrent ratio I2/I1 is considered as the detector response. For photometric detection, the device has a sensitive response covering the visible and near-IR regions, and for colour detection, the photocurrent ratio I2/I1 versus wavelength is monotonic increasing when wavelengths are larger than 430nm. A statistical method is employed for sensitivity testing, and noise analysis is performed. At low signal levels, a minimum intensity-independent noise level, mainly due to noise contributions of the coupled amplifiers, sets a detectivity of about 0.71012cmHz1/2W?1. On-chip integration of low-noise preamplifiers may further improve sensitivity performance.
cmos bdj detector sensitivity statistical method optical detection spectral characteristics