Strong Photoluminescence Enhancement of Silicon Oxycarbide through Defect Engineering

Abstract

The following study focuses on the photoluminescence (PL) enhancement of chemically synthesized silicon oxycarbide (SiCxOy) thin films and nanowires through defect engineering via post-deposition passivation treatments. SiCxOy 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 SiCxOy matrices, oxygen-rich and carbon-rich SiCxOy, 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 SiCxOy thin films were investigated to acquire further insight into the ramifications of the passivation on the carbonyl/dangling bond density and PL yield.

On-Demand CMOS-Compatible Fabrication of Ultrathin Self-Aligned SiC Nanowire Arrays

“…A decrease in refractive index upon annealing at higher temperatures was observed ( Figure 5 g), approaching the reference value for 3C–SiC (~2.7) [ 39 ]. E g values were calculated using Tauc’s law αE = B ( E − E g ) 2 , where α is the absorption coefficient, B is the slope (which is inversely proportional to the band tail width), E is the photon energy, and E g is the optical bandgap [ 29 ]. E g increased with higher annealing temperatures, approaching the reference value of ~2.4 eV for 3C–SiC [ 40 ].…”

“…Nanowire synthesis was conducted using a well-controlled thermal chemical vapor deposition (CVD) process, which has been reported previously for the synthesis of silicon carbide (SiC) and silicon oxycarbide (SiC:O) [ 29 , 30 , 31 ]. For this work, ultrathin (10 to 40 nm) SiC or SiC:O was deposited onto the HSQ ribbon array, followed by a thermal anneal for 1 hour in forming gas (5% H 2 , 95% Ar) at a temperature ranging from 900 to 1200 °C.…”

Defect‐Rich Molybdenum Sulfide Quantum Dots for Amplified Photoluminescence and Photonics‐Driven Reactive Oxygen Species Generation

“…Both spectra of the MoS 2 QDs could be resolved into two major emission peaks: one at around 464-475 nm due to intrinsic state emission (electron-hole recombination) and the other one located at around 530 nm derived from defect state emission but with a stronger PL outcome from B-QDs. [27,36] Therefore, from our previous observation, we hypothesized that the process of NaOH treatment led to electron insertion into the host phase of O-QDs (Figure 4E), inducing profound surface vacancies through high charge density of OH − and Na + intercalation into the interlayer space of MoS 2 QDs. Concomitantly, Na + interacted with the surface and edges of O-QDs, attracting the electronegative S, strained the Mo-S bond and resulted in regions of S vacancy defects.…”

Enhanced Photoluminescence of Hydrogenated Amorphous Silicon Carbide Thin Films by Means of a Fast Thermal Annealing Process

“…From the FTIR spectra, we can also observe some oxygen bonds, even when the a-Si 1−x C x :H films were deposited with a vacuum system and without any oxygen (O) flow; therefore, there was some incorporation of O into the films, which could be attributed to some contaminants such as atmospheric oxygen (CO 2 , H 2 O, N 2 ), due to vacuum leaks, impurities in the gases, pump oil backstreaming (hydrocarbons), or from the absorption of reactor surfaces (H 2 O) [18]; moreover, the PECVD deposition parameters seem to have influenced the percentage of O incorporation. Therefore, the films could be considered to be an alloy composed of Si, C, and O; that is, an amorphous silicon hydrogenated oxycarbide [14,19].…”