Abstract: The present invention provides a method of forming a silicon dioxide film containing germanium (Ge) nanocrystals, including the steps of (a) depositing Ge doped silicon dioxide on a substrate by means of atmospheric pressure chemical vapor deposition by which Si-based organic source, Ge-based organic source and ozone are to be reacted with one another, and (b) annealing the thus deposited Ge doped silicon dioxide film under non-reactive or reducing gas atmosphere at a temperature sufficient to break Ge-O bonds. The present invention makes it possible to grow Ge nanocrystals in a silicon dioxide film so that the Ge nanocrystals have a size sufficient to perform quantum confinement effects, and thereby provides a film suitable for fabrication of new optical devices and electronic devices utilizing non-linear optical characteristics.