A study of ion implantation into crystalline germanium

We report an experimental and simulation study for introducing dopant ions into (1 0 0) germanium in the energy range from 5 to 40 keV. The successful calibration of our Monte Carlo ion implantation simulator for amorphous and crystalline Ge targets is demonstrated by comparison of predicted boron profiles with SIMS data. The implantation profile in Ge is shallower than in Si for a given energy due to the larger nuclear and electronic stopping power of Ge atoms. The generated point defects and amorphized regions in the crystal are calculated by a modified Kinchin–Pease model. We found that the higher displacement energy in Ge, the stronger backscattering effect, and the smaller energy transfer from the ion to the primary recoil of a cascade are mainly responsible for the significantly reduced implantation damage in Ge. The point responses for boron implantations in Si and Ge are compared with each other. Finally the simulation results for the formation of interdigitated Ge-on-Si PIN-photodiodes are presented.