Reduction of carrier mobility in semiconductors caused by charge-charge interactions

Abstract

We investigate the effect of charge-charge interactions on carrier mobility in titanium dioxide $(\mathrm{Ti}{\mathrm{O}}_{2})$ and silicon (Si) using terahertz spectroscopy. Charge scattering times and plasma frequencies are directly determined as a function of charge density. In Si, a linear increase in scattering rate for densities exceeding ${10}^{21}\phantom{\rule{0.3em}{0ex}}{\mathrm{m}}^{\ensuremath{-}3}$ is attributed to electron-hole scattering. In contrast, in $\mathrm{Ti}{\mathrm{O}}_{2}$, charge-charge interactions are suppressed due to dielectric screening, highlighting the vastly different dielectric properties for these two materials.