Strong white light emission from SiCxOy films grown by HFCVD technique

Abstract

In this work, we present the study of a strong white emission (3.35–1.72 eV) from non-stoichiometric silicon oxycarbide (SiCxOy) films deposited by hot filament chemical vapor deposition technique (HFCVD). For the growth of SiCxOy films, carbon and silicon oxide compounds in gas phase were generated from ethanol vapor and the chemical reaction of atomic hydrogen (H°) with a solid fused quartz source, respectively. To incorporate ethanol vapor to the reaction chamber, hydrogen flow was used as a carrier gas of ethanol molecules bubbled from liquid ethanol source. The analysis of composition obtained by X-ray photoelectron spectroscopy indicates that the carbon content in the SiCxOy films increases from 3.8 to 9.3 at.% as the carrier gas flow (H2) increases from 124 to 249 sccm, respectively. Fourier transform infra-red spectroscopy shows that the increase in carbon content favors the formation of both: Si–C bonds located at about 816 cm−1 and Si–O–Si vibrations located at around 1050-1070 cm−1 the last of which associates to a SiOx network. It is observed that SiCxOy films with carbon concentrations of 3.8 at.% emit a high photoluminescence (PL) intensity, however for carbon concentrations of 9.3 at.%, the PL intensity decreases. The analysis of luminescent centers indicates that high PL response could be associated to Si-related oxygen vacancies (Si-NOVs) and Si-related oxygen deficiency centers (Si-ODCs) due to low carbon concentration into the SiCxOy films.