The CdTe cap layers were grown on CdZnTe-substrated HgCdTe (MCT) LPE epilayers by magnetron sputtering and thermal evaporation. The diffusion behaviors of Cd & Hg components and impurities (As or In) in these CdTe/MCT structures subjected to As ion implantation and various Hg overpressure annealing processes were investigated. The conclusions indicate that the defects at the CdTe/MCT interface could produce the accumulations of impurities and the distributions of induced damages (related to the cap layer structure) have a significant influence on the diffusion of components and impurities. By adjusting annealing procedures, the diffusions of components and impurities can be controlled.