Defects, diffusion and activation in ion implanted HgCdTe

The current understanding in junction formation by ion implantation in HgCdTe material is discussed. Two major techniques are available for junction formation: a traditional technique that consists of an ion implantation process (usually B or Be) followed by a diffusion of the irradiation-displaced mercury atoms (I²/DMD), and a classical technique of ion implantation followed by the electrical activation of the implanted species. The activation process could be of a diffused species from the implanted source, or of the as-implanted species (I²/AD or I²/D, respectively). A variety of junction different in nature and electrical profile have been demonstrated. The best quality devices obtained so far in Hg_1-xCd_xTe material with x = 0.2 from either technique are implanted-dif fused in nature, i.e., n-on-p of I²/DMD type (residual impurity in n-side and Hg vacancy in p-side) and p-on-n of I²/AD type (implanted As in p-side and In in the background for n-side). Examples of the best data obtained are as follows: n-on-p devices formed by the I²/DMD technique in a planar structure with a cutoff wavelength of λ_c/77 K = 9.37 μm had a zero bias resistance-area product of R₀A/40 K = 4.9×10⁶ Ω cm²; and p-on-n devices formed by I²/AD with As implants in a mesa structure with λ_c/77 K = 9.0 μm had ₀A/40 K = 3.7×10⁶ Ω cm².