The present work clarifies the role of Hg diffusion in forming ion‐implanted junctions in HgCdTe. Two experiments indicate that displaced Hg acts as a limited diffusion source. The first experiment contrastsn/pjunction electrical profiles in two HgCdTe wafers, onepdoped primarily by cation vacancies and the other primarily by the addition of As in the liquid phase epitaxy melt. The second experiment compares the carrier concentration near the junction with the residual net background doping of the sample. The results indicate that Hg released from the implant region operates as a limited diffusion source in the post‐implant anneal process. Adjusting these material and process parameters allowsn‐on‐pjunctions to be formed with a controllable electrical profile.