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This stJdy investigates the separate dark current components which are dom'nanr in the diffus'on-limited regime in MWIR n/p HgCdTe/CdTe/sapphire photodetectors. Both mesa and p.anar configurations of variable-area diodes were fabr:cated and evaluated over the temperatJre range from 78 to 250 K. Simple analytical express'ons are Jsed to calculate tne contributions of bulk, lateral and surface effects from the perimeterlarea aependence of R+l and measurement of the minority carr:er d:ffusion length. The analysis ind'cates that at 180 K the nesa diode results can oe accounted for oy bulk and lateral currents, but that the planar diodes are limiteo oy surface currents. The 780 r( median &A for the mesa jiodes ranges from 63 R cm2 for 500 x 500 pm2 d:ooe areas to 14 R cm2 for .30 x 30 pm2 aiodes at a cut-off wavelength of 4.64 pm. Scann'ng laser m'croscope neasuements determine the 180 K e ectron minority carrier diffus:on length to be 17-18um.