Strong Photoluminescence Enhancement of Silicon Oxycarbide through Defect Engineering

The following study focuses on the photoluminescence (PL) enhancement of chemically synthesized silicon oxycarbide (SiC_xO_y) thin films and nanowires through defect engineering via post-deposition passivation treatments. SiC_xO_y materials were deposited via thermal chemical vapor deposition (TCVD), and exhibit strong white light emission at room-temperature. Post-deposition passivation treatments were carried out using oxygen, nitrogen, and forming gas (FG, 5% H₂, 95% N₂) ambients, modifying the observed white light emission. The observed white luminescence was found to be inversely related to the carbonyl (C=O) bond density present in the films. The peak-to-peak PL was enhanced ~18 and ~17 times for, respectively, the two SiC_xO_y matrices, oxygen-rich and carbon-rich SiC_xO_y, via post-deposition passivations. Through a combinational and systematic Fourier transform infrared spectroscopy (FTIR) and PL study, it was revealed that proper tailoring of the passivations reduces the carbonyl bond density by a factor of ~2.2, corresponding to a PL enhancement of ~50 times. Furthermore, the temperature-dependent and temperature-dependent time resolved PL (TDPL and TD-TRPL) behaviors of the nitrogen and forming gas passivated SiC_xO_y thin films were investigated to acquire further insight into the ramifications of the passivation on the carbonyl/dangling bond density and PL yield.