Defect free visible photoluminescence from laser-generated germanium nanoparticles

Origin of room temperature visible photoluminescence (PL) from defect free germanium (Ge) nanoparticles have been discussed here. The Ge nanoparticles produced by laser-induced etching technique show broad visible PL around 2.0 - 2.2 eV at room temperature. Size dependent PL peak shift in Ge nanoparticles has been explained in terms of quantum confinement. Theoretical calculations of radiative lifetime using oscillator strength, which is closely related to the size of the nanostructures, suggests that the PL is originating from a radiative recombination process in quantum confined Ge nanostructures.