We are interested in germanium nanocrystal density and size effects on the carrier storage and emission processes. For this purpose, high frequency capacitance-voltage and current-voltage characteristics were performed for temperatures varying from 300 to 77 K. Ge nanocrystals were deposited on a silicon dioxide/p-doped silicon structure and capped with a thin amorphous silicon layer. Results evidenced an electron storage phenomenon in nanocrystals that presented two different behaviors depending on the temperature. For temperatures higher than ∼140 K, the storage was mainly controlled by the nanocrystal density. At low temperatures the storage was reduced due to lowering of the tunneling barrier that resulted from a carrier quantum confinement process. Thermal activation energy of the carrier emission process was revealed as varying linearly with nanocrystal energy band gap. Activation energy was identified as a barrier height to be overcome by the emitted electrons.