Te implantation in Ge(001) for n-type doping applications

Abstract

5×1015 Te+ ionscm−2 were implanted in an Ge(001) substrate using an industrial implanter with a Te+ beam energy of 180keV. In addition to usual implantation-mediated defects observed in Ge with usual dopants, Te implantations lead to the formation of amorphous surface GeO clusters exhibiting micrometer scale sizes, as well as deep extended defects. Implantation defects promote the formation of two distributions of dislocation loops and clusters located at two different depths in the Ge substrate during annealing. No interactions between Te atoms and dislocation loops were observed. However, the formation of non-equilibrium Te–Ge clusters, probably mediated by Ge self-interstitials, was found to prevent the Te solubility to exceed ~5×1019cm−3 in Ge. The regular implantation method is shown to be ineffective for the production of high level n-type Ge doping using Te, due to the important Ge damage caused by Te implantation.