Decay Kinetics of Electron-Hole-Drop and Free-Exciton Luminescence in Ge: Evidence for Large Drops

Following pulsed laser excitation of Ge, we observe both the free-exciton (FE) and electron-hole-drop (EHD) luminescence decay. The kinetics are in excellent agreement with exact numerical solutions of the rate equations of Pokrovskii and Hensel, Philips, and Rice, yielding EHD and FE total lifetimes 35.6 ±{} 0.5 and 7.7 ±{} 0.5 {μ} sec, respectively, the EHD radiative enhancement factor ρ=5.1, and values of the thermionic emission and backflow coefficients. The data suggest the production of EHD of diameter {~} 0.4 mm.