Role of surface passivation on visible and infrared emission of Ge quantum dots formed by dewetting

[摘要] The dual action of oxide-related defects in the visible and infrared emission of germanium (Ge) self-assembled quantum dots (QDs) is discussed. TheGe particleswere fabricated by solid-state dewetting on a thin layer of SiO$_2$. Subsequent surface passivation by amorphous silicon was carried out for several samples. All samples were encapsulated by SiO$_2$. Atomic force microscopy analysis indicates a linear relationship between the size of QDs and the initial thickness of the amorphous Ge films. The crystallization of the QDs was evidenced by transmission electron microscopy and Raman spectroscopy. Photoluminescence measurements show that the main visible emission is blue-green centred around 520 nm. The luminescence attributed to the radiative recombination of quantum-confined excitons is only observed when the surfaceis in-situ passivated prior to the deposition of the oxide matrix. The results of this work are helpful for optimizing the performance of the optoelectronic devices based on the infrared emission of Ge nanocrystals.

[学科分类] 材料工程

[关键词] Solid-state dewetting;Ge quantum dots;oxide-related defects;photoluminescence.