Raman scattering by intervalley carrier-density fluctuations in n-type Si: Intervalley and intravalley mechanisms

We present an extensive study of Raman scattering by intervalley density fluctuations in n-type Si for a wide range of electron concentrations (8×1018<eqNe<eq1020 cm-3), temperatures (80473 K), and laser frequencies (1.16 to 2.54 eV). The experiments were performed with a Raman (>20 cm-1) and a Fabry-Perot Brillouin spectrometer (<20 cm-1). The results indicate that both nonlocal intravalley diffusion and local intervalley scattering contribute to the light scattering. The measured scattering efficiencies can be quantitatively interpreted without recourse to adjustable parameters. Failure to observe the scattering in ion-implanted laser-annealed samples is also discussed.