Design optimization of Superlattice Type II IR detection modules with temporal signal coincidence in two spectral ranges

摘要

3rd Generation IR detectors providing e.g. dual-color capability are of great benefit for applications like aircraft missile approach warning systems using this feature for achieving low false alarm rates by separating the hot CO_2 missile plume from background and clutter. AIM and IAF selected antimonide based type II Superlattices (SL) for such kind of applications.The type II SL technology provides an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. IAF and AIM already managed to realize a dual-color 384×288 IR-Module based on this technology. It combines spectral selective detection in the 3-4 μm wavelength range and 4-5 μm wavelength range in each pixel with coincident integration in a 384×288×2 format and 40 μm pitch. Excellent thermal resolution with NETD < 17 mK @ F/2, 2.8 ms for the longer wavelength range (red color) and NETD < 30 mK @ F/2, 2.8 ms for the shorter wavelength range (blue color) were already reported. In order to increase further the quantum efficiency and subsequently decrease further the spectral crosstalk between the two colors the layer thickness of the SL-layer was optimized. This paper is intended to present the current status and trends at AIM on antimonide type II Superlattices (SL) IR module developments for ground and airborne applications in the high performance range, where rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - require temporal signal coincidence with integration times of typically 1ms.