3rd gen focal plane array IR detection modules and applications
Bildfeld-Mosaik-Infrarot-Detektoren der dritten Generation und deren Anwendungen
The 3rd generation of infrared (IR) detection modules is expected to provide advanced features like higher resolution 1024x1024 or 1280x720 pixels and/or new functionalities like multicolor or multi band capability, higher frame rates and better thermal resolution. This paper is intended to present the current status at AIM on the Mercury Cadmium Telluride (MCT), quantum well (QWIP) and antimonide superlattices (SL) detection modules for ground and airborne applications in the high performance range. For high resolution a 1280x720 MCT device in the 3-5µm range (MWIR) is presently under development. For spectral selective detection, a QWIP detector combining MWIR and 8-10µm (LWIR) detection in each pixel has been developed in a 384x288x2 format with 40 µm pitch, NETD < 35mk @ F/2, 6,8 ms for both peak wavelengths (4.8 µm and 8.0 µm). The device provides synchronous integration of both bands for temporal and spatial coincidence of the events observed. QWIP dual band or dual color detectors provide good resolution as long as integration times in the order of 5-10ms can be tolerated. This is acceptable for all applications where no fast motions of the platform or the targets are to be expected. For rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - a material system with higher quantum efficiency is required to limit integration times to typically 1ms. For this case, several companies work on molecular beam epitaxy (MBE) of MCT to have access to double or multi layer structures. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The SL technology provides - similar to QWIP's - an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. While promising results on single SL pixels have been reported since many years, so far no SL based detection module could be realized. Just recently, IAF and AIM managed to realize first most promising SL based detectors. Fully integrated IDCA's with a MWIR SL device with 256x256 pixels in 40µm pitch have been integrated and tested. The modules exhibit excellent thermal resolution of NETD<12mk @ F/2 and 5ms. The next step will now be to stabilize the technology and to start the development of a dual color MWIR device based on SL technology and the existing 384x288 read out circuit (ROIC) used in the dual band (QWIP) device.