HgCdTe is the most important material for LWIR detectors, and n on p type with a planar structure using ion-implantation technique is still the state-of-the-art for fabricating infrared focal plane arrays (IRFPAs). Nevertheless, the implantation introduces lattice damage and increases the dark current, which are expected to be reduced by an annealing process. In this paper, HgCdTe diodes ((lambda) coutoff,77k equals 11.0 micrometers) were fabricated on Hg-vacancy doped p type HgCdTe wafers grown on CdTe substrates by LPE, and junction was formed with boron ion-implantation. The annealing process was implemented after the ion-implantation at various temperatures, from 120 degrees Celsius to 200 degrees Celsius, under N2 gas atmosphere. The performance of the annealed diodes was investigated in detail by model fitting analysis. This current model includes four dark current components, i.e. diffusion current, generation-recombination current, trap- assisted tunneling current and band to band tunneling current. Measurements and analyses of 1/f noise characteristics were performed at several bias voltages for samples annealed at 150 degrees Celsius. Among them, both devices annealed for 30, and 60 minutes showed equivalent RoA values, but the latter had lower level 1/f noise current at small reverse bias voltage. From the model fitting analysis, the sample annealed at 150 degrees Celsius for 60 minutes was found to be generation- recombination limited at the small reverse bias while that for 30 minutes was to be trap-assisted tunneling limited. This reduction of 1/f noise was attributed to the decreased trap density in the vicinity of pn junction.