Impurity Effects on Strain-Confined Electron-Hole Liquid in Germanium I. Photoluminescence Studies on Recombination Dynamics

Abstract

This paper deals with impurity effects on recombination dynamics within strain confined electron-hole liquid (SCEHL) in Ge, based on time-resolved measurements of photoluminescence intensity. Double acceptors, Be and Zn, are taken as well as single acceptor In. The double acceptors strongly accelerate non-radiative recombination with SCEHL. At 1.8 K, recombination rate per impurity is 7.2×10⁻¹⁰ cm³ s⁻¹ for Be, and 2.6×10⁻¹⁰ cm³ s⁻¹ for Zn. These are more than ten times as large as that for In, 2.2×10⁻¹¹ cm³ s⁻¹. Especially, recombination through Be impurity is due to multiphonon-emission process. The Mott criterion is introduced as a qualitative measure for the difference between the double and the single acceptors. Free-exciton capture cross section by Be or In impurity is also derived.