Raman scattering determination of carrier distribution in GaP diodes

Using a Raman microscope we have studied Raman scattering from plasmon-LO-phonon coupled modes in the cross section of GaP diodes. The line shape analysis of the coupled mode has provided the thermal-equilibrium carrier concentration and mobility. Their distribution is determined from the spatial variation of the spectra. The carrier distribution thus obtained is consistent with that estimated from capacitance measurements. The result demonstrates that the Raman microprobe is a powerful method for determining the distribution of the carrier concentration and mobility in semiconductor devices without electric measurements using electrodes.