A 320 x 240 pixels quantum well infrared photodetector array for thermal imaging

Infrared pixel detectors sensitive to radiation in the wavelength range 8 t o 9 mu m have been fabricated and evaluated. The detectors have 320 x 240 p ixels and consist of two parts. One is the infrared sensitive part with a q uantum well structure based on n-doped AlGaAs/GaAs. The other part is a rea dout circuit in standard CMOS technology. The two parts are hybridized by a flip-chip technique using indium bumps. Optical coupling into the detectors is performed by using optimized, etched , two-dimensional gratings combined with GaAs substrate thinning down The t hinning removes the problem with thermal mismatch, enhances the absorption and eliminates optical crosstalk between pixels. The intended operating tem perature range is 70-73 K, achievable by a miniature Stirling cooler. Excel lent wafer uniformities resulting in responsivity uniformities of 3.3% acro ss an array are found, and a temperature resolution NETD (noise equivalent temperature difference) = 20 mK is achieved.