Resistance-area product of diodes in a long-wavelength infrared HgCdTe mosaic array

A long wavelength infrared (LWIR) 2D (mosaic) diode array has been studied by numerically solving the diffusion equation in terms of thermally generat ed carriers in a n(+)-on-p HgCdTe diode in an array environment. The result s are presented in terms of the resistance-area (RA) product, in the diffus ion-limited case. The results are compared with analytical expressions in t he limiting case of the infinite diode. For a finite diode, with a definite junction depth, and a diode size that is smaller than the pitch, the RA, o btained from quasi-3D calculations, is smaller than that expected for the i nfinite diode case, the deviation being greater for small diodes. Commonly in the literature, the theoretical values of the infinite (1D) diode - whic h are overestimates - are stated as experimental targets. In the present ca lculations, the volume of the diode is considered to consist of two parts: one that contributes to the lateral diffusion current that is collected by the four lateral faces of the diode junction, and another that is the 'norm al' diffusion current, collected by the planar part of the junction from th e volume 'under' the diode. For the infinite diode case, only the latter co mponent exists. The effect of the perimeter-to-area ratio on the RA in an a rray environment has been studied. The effective diffusion length associate d with the finite diode geometry in an array differs from the standard diff usion length. (C) 2002 Elsevier Science B.V. All rights reserved.