Defect-induced photoluminescence from tetraethylorthosilicate thin films containing mechanically milled silicon nanocrystals

Abstract

In this work, the unique synthesis of mechanically milled silicon nanocrystals (Si nc) embedded in tetraethylorthosilicate (TEOS) thin films is reported. A series of Si nc, with sizes ranging from 10to25nm, have been synthesized using mechanical milling. For both the milled Si nc and milled Si nc embedded in TEOS thin film, infrared absorption and photoluminescence results show that the photoluminescence (PL) is not a consequence of quantum confinement, amorphous Si component, or Si–OH or Si–H bonds. The defects, such as nonbridging oxide hole centers (NBOHCs), in amorphous SiO2 are probably the dominant mechanism for the PL of milled Si nc embedded in TEOS thin films. In addition, PL excitation results reveal oxidation-induced strain between the interfaces of milled Si nc∕SiO2 has also generated a new luminescence center. This luminescence center is similar to the NBOHCs attributed to interfacial strain.