Midinfrared picosecond spectroscopy studies of Auger recombination in InSb

Abstract

A midinfrared picosecond spectrometer based on an ${\mathrm{Er}}^{3+}$ laser-pumped optical parametric generator has been used to study Auger recombination processes in intrinsic InSb at room temperature. After carrier excitation by a 100-psec \ensuremath{\lambda}=2.8 \ensuremath{\mu}m ${\mathrm{Er}}^{3+}$ laser pulse the sample transmission change due to excess carriers was probed, using short pulses of wavelengths varying in the range 4--6 \ensuremath{\mu}m, as a function of time delay. It was shown that over the measured range of carrier densities (n=${10}^{16}$--${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) the momentum-conserving conduction--heavy-hole--heavy-hole--light-hole Auger process was the predominant channel for electron-hole recombination with a quadratic rather than a cubic dependence of recombination rate on carrier density. The effective Auger lifetime scales as ${\mathrm{\ensuremath{\tau}}}_{\mathrm{Aug}}^{1\mathrm{\ensuremath{-}}}$=${\mathit{C}}_{2}$n with ${\mathit{C}}_{2}$=7.4(\ifmmode\pm\else\textpm\fi{}1.5)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}9}$ ${\mathrm{cm}}^{3}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. This type of carrier concentration dependence is in accordance with theoretical predictions for semiconductors in which the electron component of the carrier population is degenerate.