Quasielastic Electronic Light Scattering in Semiconductors at Low Concentrations of Current Carriers

Abstract

The Energy and momentum conservation laws in an elementary process of quasielastic electronic light scattering can be expressed in the form ⁽¹⁾

$$ \mathop{E}\nolimits_{{\vec{p} + h\vec{k}}} - \mathop{E}\nolimits_{{\vec{p}}} = h\omega $$

((1))

where $\mathop{E}\nolimits_{{\vec{p}}}$ is the energy of an electron with quasimomentum $\vec{p}$, while $\mathop{h}\nolimits_{{\vec{k}}}$ and hω are the momentum and energy transferred in the light scattering process. The majority of the electronic light scattering experiments have been carried out on heavily doped semiconductors with high current carrier concentrations n ≳ 10¹⁶ cm^-3, when the condition for strong screening holds

$$ k{r_s} \ll 1\;\,, $$

(2)

where r_s is the electron screening radius. Light scattering is possible in this case only due to special mechanisms providing the neutrality condition. Quasielastic light scattering spectra have a Lorentzian shape which indicates the diffusive motion of carriers in heavily doped materials⁽²⁾.