The light-emitting properties of Ge nanocrystals grown by pulsed laser deposition

The light-emitting properties of Ge nanocrystals on an Si(100) matrix prepared by pulsed laser deposition (PLD) and in situ rapid thermal annealing (RTA) were studied. The photoluminescence (PL) intensity becomes stronger and the FWHM decreases from 100 to 50 meV when the annealing temperature varies from 300 to 600 °C, reflecting that the as-deposited amorphous Ge has been effectively crystallized by high temperature. Also, the PL peak significantly shifts from 0.786 to 0.732 eV and the FWHM of the peaks increases from 30 to 70 meV as deposition time increases from 30 s to 8 min, indicating that the PL of the Ge nanocrystals has a large quantum size effect. In addition, the PL peaks increase initially and then decrease with increasing reversed bias voltage, which is attributed to the tunnelling effect of the carriers.