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

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Abstract
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<eqNe1020 cm−3), temperatures (80–473 K), and laser frequencies (1.16 to 2.54 eV). The experiments were performed with a Raman (ω>20 cm−1) and a Fabry-Perot ‘‘Brillouin’’ spectrometer (ω<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.