Sandwich-structured thin film of silicon nanoparticles embedded in Al2O3 matrices

Abstract

Silicon nanoparticles embedded in the host matrix of an Al2O3 thin film, with a thickness of about 260 nm, were prepared by using the pulsed laser deposition method. The laser target consisted of a small silicon wafer glued onto the surface of a circular Al2O3 plate, which was set to rotate uniformly when laser-ablating. TEM and EDS results showed that the films consisted of silicon nanoparticles in the form of nanocrystals with diameters of less than 6 nm dispersed in the amorphous Al2O3 matrices. A secondary ion mass spectroscopy depth profile of the silicon content of the film indicated that the silicon nanoparticles in the Al2O3 matrices were arranged in fairly well demarcated thin layers sandwiched between layers of the host material. FTIR results evidently suggested that the encapsulating amorphous Al2O3 material forms a good host for the prevention of atmospheric oxidation of the silicon nanoparticles. However, prolonged annealing can cause the silicon nanoparticle surface interfacing the host material to be oxidized by the oxygen mostly from the Al2O3 molecules and to be bonded to the Al or O-Al bonds.