Modeling of boron and phosphorus implantation into (100) germanium

Boron and phosphorus implants into germanium and silicon with energies from 20 to 320 keV and ion doses from 5 × 10¹³ to 5 × 10¹⁶ cm^-2 were characterized using secondary ion mass spectrometry. The first four moments of all implants were calculated from the experimental data. Both the phosphorus and boron implants were found to be shallower in the germanium than in the silicon for the same implant parameters and high hole concentrations, as high as 2 × 10²⁰ cm^-3, were detected by spreading resistance profiling immediately after boron implants without subsequent annealing. Channeling experiments using nuclear reaction analysis also indicated high substitutional fractions (∼ 19%) even in the highest dose case immediately after implant. A greater straggle (second moment) is, however, observed in the boron implants in the germanium than in the silicon despite having a shorter projected range in the germanium. Implant profiles predicted by Monte Carlo simulations and Lindhard-Scharff-Schiott theory were calculated to help clarify the implant behavior. Finally, the experimentally obtained moments were used to calculate Pearson distribution fits to the boron and phosphorus implants for rapid simulation of nonamorphizing doses over the entire energy range examined.