Percolation problem in atomic transport in Hg1-xCdxTe

Using high-resolution x-ray diffraction for precise measurements of structu ral modifications in boron-implanted Hg1-xCdxTe layers, we found a percolat ion problem in the long-range diffusion of Cd interstitials through the Cd, Hg sublattice. The percolation threshold x(c) = 0.265 is in agreement with the calculated one, x(th) = 0.278, for dumbbell interstitials diffusion in the fee lattice [J. Bocquet, Phys. Rev. B 50, 16 386 (1994)]. These findin gs were supported by high-resolution scanning electron microscopy images, t aken under magnification x 400 000, in which very different post-implantati on surface recovery (due to a flux of interstitials from an interior to the crystal surface) was observed below and above x = x(c). Measurements of x- ray diffraction profiles in samples, implanted and annealed at 150-350 degr ees C, allowed us to determine an energy barrier, Delta E = 0.31 eV, betwee n Cd-Cd and Cd-Hg dumbbell configurations. [S0163-1829(99)10547-2].