Fe2+-Fe3+ level as a recombination center in In0.53Ga0.47As.

Abstract

Thermal emission of electrons and holes from the ${\mathrm{Fe}}^{2+}$-${\mathrm{Fe}}^{3+}$ level in ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As is investigated in detail. Iron is found to act as a recombination center in this material, since majority carrier emission is observed in n- and in p-type layers. The interaction of the Fe level with free carriers is strongly localized, resulting in statistical distributions of the apparent activation energy and the electron and hole capture cross sections due to the statistical distribution of the occupancy of the cation sites by indium and gallium ions. A detailed general model for carrier capture and emission of a recombination center in a ternary alloy as observed by deep-level transient spectroscopy (DLTS) is developed. The mean energy position of ${\mathrm{Fe}}^{2+}$-${\mathrm{Fe}}^{3+}$ is determined as 0.39\ifmmode\pm\else\textpm\fi{}0.02 eV above the valence-band edge. This value agrees perfectly with the prediction of the internal reference rule. The electron and hole capture cross sections are distributed over nearly two orders of magnitude, causing a shift of the DLTS peaks with filling pulse width and nonexponential refilling of the traps. The mean values at 250 K are ${\mathrm{\ensuremath{\sigma}}}_{\mathit{n}}$=8\ifmmode\pm\else\textpm\fi{}5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}18}$ ${\mathrm{cm}}^{2}$ and ${\mathrm{\ensuremath{\sigma}}}_{\mathit{p}}$=2\ifmmode\pm\else\textpm\fi{}1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}17}$ ${\mathrm{cm}}^{2}$ for the electron and hole capture cross sections, respectively.