<title>Required composition uniformity of Hg1-xCdxTe substrate for focal plane arrays</title>

This paper presents a comparison of theoretically predicted spatial NETD and mean temporal NETD as a function of the composition uniformity of Hg_1-xCd_xTe substrate used in the fabrication of IR detector arrays. The prediction of the spatial NETD is based on the residual spatial noise left behind in the FPA after implementing a linear two point nonuniformity compensation algorithm. The effect of using an optical filter on the spatial NETD is also included to show that the specifications on the composition uniformity of the Hg_1-xCd_xTe substrate can be partially relaxed by using an optical filter whose cut-off wavelength is less than the cutoff wavelength of the photodiodes of mean response. The composition uniformity leading to temporal noise rather than the spatial noise limited performances are suggested to be indicating the required composition uniformity of Hg_1-xCd_xTe substrate for focal plane arrays (FPA). The results are presented for both MWIR and LWIR HgCdTe hybrid FPAs.