The migration of In in Hg1-xCdxTe, where x ranged from 0.2 to 0.3, was studied by using a 2-zone furnace technique at temperatures ranging from 240 to 380C. The second-zone temperature was chosen so as to maintain a constant concentration of Hg vacancies if no In was present. It was found that the typical In profile consisted of an erfc-like segment at high concentrations and an abrupt profile for low concentrations at the diffusion front. The depth of the latter coincided very well with the depth of the n-type region. An electron concentration of up to 5 x 1018/cm3 was observed. The electrical activation decreased with increasing In concentration, as revealed by differential Hall effect measurements. The chemical In profiles were explained in terms of interstitial diffusion; together with 2 incorporation mechanisms (Frank-Turnbull, kick-out), thus giving differing net charge transfers. A numerical diffusion model was proposed that was based upon the assumption of local equilibrium in site occupation and a linear response of the change in defect concentration in response to deviations from equilibrium. Although the profiles depended strongly upon the In surface concentration, a concentration-independent diffusion coefficient for interstitial In was found. This was characterized by a pre-exponential value of between 5.4 x 10-5 and 9.2 x 10-5cm2/s and an activation energy of 0.922eV.

G.Weck, K.Wandel: Journal of Vacuum Science and Technology A, 1994, 12[6], 3023-32