Small pitch resonator-QWIP detectors and arrays

We are developing small pixel 12-μm pitch resonator-QWIPs for infrared imaging at 8 μm and 10 μm. The materials and geometries are designed to yield 44% quantum efficiency (QE) at 1.0 × 1018 cm−3 doping and 56% at 1.2 × 1018 cm−3 for the 8 μm detectors and 47% at 1.0 × 1018 cm−3 for the 10 μm detector. Because of production variability and excess detector tunneling current at large bias, the maximum QE for the 8 μm detectors is measured to be 24.6% and 56.4%, respectively, while that for the 10 μm detector is 44%. Focal plane arrays of 1280 × 1024 resolution were produced from the lower doping, 8 μm material. Their performance is the same as the test detectors up to the maximum internal bias of the readout circuit. From the test detector I-V characteristics, the performance can be further projected to higher bias, at which the FPAs can offer 23 mK sensitivity at 3.7 ms integration time from the lower doping material and 21 mK at 3.2 ms from the higher doping material. For the 10 μm FPAs, the sensitivity is projected to be 30 mK at 3.8 ms. Therefore, we have demonstrated high sensitivity and fast R-QWIP FPAs down to 12-μm pitch. To expand the application envelope of the resonator-pixel technology, we have deigned resonant geometries for other infrared materials. Experimental efforts are underway.