SPECIFIC BEHAVIOR OF CDTE ION-IMPLANTATION DAMAGE

In order to study the damage produced as a function of both the chemical nature of the ion and the implantation energy, [111] CdTe single crystals were implanted with 150 keV Mn and 50, 100 and 200 keV P ions. Analysis of the damage was carried out by Rutherford backscattering spectrometry and ion channeling measurements using He-4 beams at different energies. These measurements show that the disorder induced by ion implantation in CdTe exhibits specific features: (i) saturation of damage without reaching the amorphous state; (ii) existence of an almost undamaged near-surface region. In fact, whatever the implantation conditions, the normalized channeling yield (which is a measure of the integrated disorder) reaches the value of 0.6-0.7 at saturation and the low damaged layer depth is about 40 nm thick. The channeling measurements are consistent with a previous study in which the residual damage was identified as small-sized dislocation loops mainly located beyond the ion projected range Rp. These results are interpreted as indicating a high mobility of defects in CdTe together with a high efficiency of the surface in their recombination process, and the role played by the dislocation-loop-induced stress.