Study of carrier concentration profiles in Al-implanted Ge by micro-Raman spectroscopy under different excitation wavelengths

The distribution profile of Al implanted in crystalline Ge has been investigated by micro-Raman spectroscopy. Using different excitation laser lines, corresponding to different optical penetration depths, the Al concentration at different depths beneath the sample surface has been studied. We have found a strong correlation between the intensity of the Al–Ge Raman peak at ~370 cm1, which is due to the local vibrational mode of substitutional Al atoms, and the carrier concentration profile, obtained by the spreading resistance profiling analysis. A similar connection has been also observed for both shape and position of the Ge–Ge Raman peak at ~300 cm1. According to these experimental findings, we propose here a fast and nondestructive method, based on micro-Raman spectroscopy under different excitation wavelengths, to estimate the carrier concentration profiles in Al-implanted Ge.