Studies on the diffusion of iodine into CdTe at a temperature of 20°C using four widely differing types of diffusion sources are compared and discussed. The concentration profiles were measured using either a radiotracer sectioning (RTS) technique or secondary ion mass spectrometry (SIMS).
The profiles were composed of four parts to which a computer package consisting of the sum of four complementary error functions (erfc) gave accurate fits, providing four empirical values of the diffusivity. The diffusivities for the fastest component in all four cases were in agreement (∼2 × 10−14 cm2 s−1) and were consistent with previously published data. These results indicate that when iodine is diffused from the vapour it is not a suitable long-termstable dopant in devices where sharp junctions are required.