The diffusion of In and Na into Cl-doped material, from the vapour phase, was studied at temperatures ranging from 470 to 970K. The diffusivity was determined by means of layer stripping and Hall-effect measurements. It was found that the results depended upon the hole concentration of the samples (figures 13 and 14).

The data for In diffusion could be described by the expression:

D (cm2/s) = 1.17 exp[-1.68(eV)/kT]

when the hole concentration was between 1016 and 2 x 1016/cm3, by the expression:

D (cm2/s) = 0.14 exp[-1.98(eV)/kT]

when the hole concentration was between 2 x 1014 and 3 x 1014/cm3, and by the expression:

D (cm2/s) = 4.02 x 10-6exp[-0.46(eV)/kT]

when the hole concentration was between 109 and 1010/cm3. The data for Na diffusion could be described by the expression:

D (cm2/s) = 1.18 x 10-6exp[-0.25(eV)/kT]

when the hole concentration was between 109 and 1010/cm3, and by the expression:

D (cm2/s) = 8.97 x 10-5exp[-0.62(eV)/kT]

when the hole concentration was between 1011 and 1012/cm3. The effect of the holes was explained in terms of vacancy diffusion mechanisms. It was concluded that In and Na diffusion in this material occurred via a dissociative mechanism, and that the solubility and activation energy of In and Na were governed by the degree of doping. A vacancy diffusion mechanism predominated in Cl-doped material when the Cl content was at the intrinsic impurity level of about 1016/cm3.

J.M.Ivanov, G.S.Pavlova, E.L.Kanunova: Izvestiya Akademii Nauk SSSR - Neorganicheskie Materialy, 1988, 24[12], 1959-62. (Inorganic Materials, 1989, 24[12], 1681-4)

Figure 15

Diffusivity of Mn in CdTe as a Function of Temperature

(a: In-doped, b: undoped)