A detailed theory of the nucleation of electron-hole drops (EHD) from a gas of free excitons (FE) in Ge is presented, together with a systematic experimental study of hysteresis and threshold phenomena in the luminescence of optically excited crystals of ultrapure Ge. The non-equilibrium rates of EHD formation and breakup and the concentration of EHD in dynamic equilibrium with the FE gas were calculated including the effects of the EHD surface energy w and the EHD lifetime. Large metastable and non-equilibrium effects are found. These results were used to quantitatively predict for Ge under continuous excitation: (1) the EHD concentration and size vs. excitation level and history of excitation; (2) the metastable time development of the EHD concentration; (3) mathematically well-defined FE density thresholds for the formation and destruction of EHD and thus the FE-EHD phase diagram including the effects of metastablity and the EHD lifetime; (4) a procedure to accurately determine the EHD surface energy from the threshold data; and (5) limits to the steady-state EHD radius vs. temperature.
- Pub Date:
- Physics: Condensed Matter;
- Holes (Electron Deficiencies);
- Electron Transitions;
- Hole Distribution (Electronics);
- Hole Mobility;
- Solid-State Physics