Demonstration of a 25μm pitch TV/4 dual-band HgCdTe infrared focal plane array with spatial coherence

The purpose of this paper is to present the electro-optical performances of dual-band detector working in a fully spatially coherent mode, with small pixel pitch. The successive steps of device fabrication are first exposed including molecular beam epitaxy, technological processing and readout circuit design. It is shown that very high quality multiple layer heterostructures of HgCdTe can be grown and processed into 256x256 arrays of 25μm pitch mesas, each mesa including two photodiodes with different cut-off wavelength ranging in the midwave infrared (MWIR). Characterization of these focal plane arrays (FPAs) shows very good homogeneity, low defect density and operabilities usually above 99% for both responsivity and noise equivalent thermal difference (NETD).