Probing the carrier concentration profiles in phosphorus-implanted germanium using infrared spectroscopic ellipsometry

摘要

Spectroscopic ellipsometry with photon energy in the 0.045-0.65 eV range was used to investigate germanium samples implanted with 30keV phosphorus ions and annealed at 700 ℃. The infrared response of implanted layers is dominated by free carrier absorption which is modeled using a Drude oscillator. The carrier concentration profiles were modeled using an error function, and compared with those obtained by electrochemical capacitance-voltage profiling and secondary ion mass spectrometry. In the flat region of the carrier concentration profile, average carrier concentration and mobility of 1.40 × 10~(19) cm~(-3) and 336 cm~2V~(-1)s~(-1), respectively, were obtained. A phosphorus diffusivity of ～1.2 × 10~(-13) cm~2/s was obtained. The mobility versus carrier concentration relationships obtained for the implanted samples are close to the empirical relationship for bulk Ge.