Investigations of condensation phenomena of electron-hole drops in pure Ge

We have performed electron-hole drop (EHD) luminescence threshold experiments in conditions where an optical hysteresis can be observed. The characteristics of the thresholds are investigated and support the idea of supersaturation to create EHD. A simple model of the growth time of embryos shows that this requirement can explain the discrepancy between the spectroscopic and thermodynamic values of the exciton work function. From our calculations we deduce for the EHD surface energy a value in range of 1.8-2.6 erg/${\mathrm{m}}^2$.