The diffusion of Na into Cl-doped material, from the vapor phase, was studied at 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 (figure 20). The data 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 Na diffusion in this material occurred via a dissociative mechanism, and that the solubility and activation energy of 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 21

Tracer Diffusion Coefficient of the Fast Component of P in CdTe

(filled symbols: 950C, open symbols: 900C)