Efficient green-luminescent germanium nanocrystals

Highly efficient 'deep-green' luminescent germanium nanocrystals (Ge NCs) have been synthesized by a one-step laser ablation process. The NCs are thoroughly characterized by TEM, Raman and optical spectroscopic techniques. The relationship between the size and the emission is investigated through spectroscopic analyses to reveal the appearance of the quantum confinement effect. Due to the strong quantum confinement of photogenerated carriers in diamond cubic Ge NCs and well-controlled size distribution, both a full width half maxima (FWHM) of the photoluminescence (PL) (about 55 nm) and a 17% absolute PL quantum yield (QY) of the Ge NCs in thin film form are drastically improved.