The diffusion mechanisms of ion-implanted As and Sb in material which had been grown by using metalorganic chemical vapor deposition were studied. A diffusion model was developed on the basis of chemical analyses, which had been performed using secondary ion mass spectroscopy, and a Gaussian theoretical model. The nature of the As and Sb diffusion mechanisms, and the various components of the diffusion profile, were investigated. The most governable mechanism was found to be the atomic vacancy-based component in which As and Sb began on the Te sub-lattice. The associated diffusion coefficients, of 3 x 10-14 at 400C and 2 x 10-13cm2/s at 450C for As, and 9 x 10-15 at 350C and 4 x 10-13cm2/s at 400C for Sb, were deduced from the experimental data. The dislocation density and its distribution were suggested to be the main reasons for the enhancement of As diffusion in the tail components. A suitable choice of implantation and annealing conditions reduced the tail components of the diffusion profile for a given dislocation density. High-performance p-on-n photodiodes at 77K were prepared by diffusing As, from implanted and grown sources, into n-type In doped (Cd,Hg)Te which had been grown on GaAs/Si substrates.

Diffusion of As and Sb in HgCdTe. L.O.Bubulac, C.R.Viswanathan: Journal of Crystal Growth, 1992, 123[3,4], 555-66

Figure 1

Diffusivity of Cd in CdTe

(filled point: Astles & Blackmore [1986], dotted line: Borsenberger & Stevenson [1968], dotted line: extrapolation of Whelan & Shaw [1967])