We report the results of annealing effect on the Hg0.78Cd0.22Te diodes fabricated by ion-implantation technique. The annealing was performed after flip-chip bonding with Si substrate. The performances of the diodes, before and after the annealing process, were investigated in detail by model fitting analyses. This model includes five current components, such as diffusion current, generation- recombination current, band to band tunneling current, trap- assisted tunnelling current, and photo current. Especially, in the view of a trap-assisted tunneling mechanism, newly developed model is proposed with the introduction of the Poole-Frenkel effect. Using this model, it is well explained that measured RoA product is much lower than their theoretical values in the ideally diffusion limited or generation- recombination limited cases. By flip-chip bonded annealing, RoA products of the diodes were increased and dark currents were decreased. From the model fitting, the improvements are explained by the change of carrier concentration profile in a p-n junction and the reduction of trap density by the annealing process.