Free-carrier density determination in p-type GaAs using Raman scattering from coupled plasmon-phonon modes

A nondestructive optical means of determining the activated hole concentration in p-type polar semiconductors is described. The Raman spectra from coupled plasmon-longitudinal-optical-phonon modes in five samples of Be-doped GaAs are measured and fitted using a theory which takes into account the degenerate light- and heavy-hole valence bands. The results indicate that coupled plasmon-longitudinal-optical-phonon modes in p-type material differ both quantitatively and qualitatively from those in n-type semiconductors.