Defect Emission and Optical Gain in SiC_xO_y:H Films

Abstract

Luminescent SiCO:H films, which are fabricated at different CH flow rates using the plasma-enhanced chemical vapor deposition (PECVD) technique, exhibit strong photoluminescence (PL) with tuning from the near-infrared to orange regions. The PL features an excitation-wavelength-independent recombination dynamics. The silicon dangling bond (DB) defects identified by electron paramagnetic resonance spectra are found to play a key role in the PL behavior. The first-principles calculation shows that the Si DB defects introduce a midgap state in the band gap, which is in good agreement with the PL energy. Moreover, the band gap of a-SiCO:H is found to be mainly determined by Si and C atoms. Thus, the strong light emission is believed to result from the recombination of excited electrons and holes in Si DB defects, while the tunable light emission of the films is attributed to the substitution of stronger Si-C bonds for weak Si-Si bonds. It is also found that the light emission intensity shows a superlinear dependence on the pump intensity. Interestingly, the film exhibits a net optical gain under ultraviolet excitation. The gain coefficient is 53.5 cm under a pumping power density of 553 mW cm. The present results demonstrate that the SiCO system can be a very competitive candidate in the applications of photonics and optoelectronics.

Tailored Synthesis of Pt‐Nanoparticle‐Modified Mesoporous TiO2 Popcorn‐Like Nanostructures for Photocatalytic Applications

“…As compared with pure TiO 2 , the DOS in the Pt/TiO 2 possesses plentiful electronic states cross Fermi level, whereby ensuring a higher carrier mobility. [25] The electronic localization function (ELF) maps are also measured to map the likelihood of finding an electron between neighborhood atoms, which gives a better understanding of carrier migration. On the basis of the ELF of Pt/TiO 2 , it is evident that a strong interface interaction appears between Pt and O elements, creating more transfer channels for electrons.…”

“…The VB and CB of TiO 2 are mainly composed of Ti 3d and O 2p. As compared with pure TiO 2 , the DOS in the Pt/TiO 2 possesses plentiful electronic states cross Fermi level, whereby ensuring a higher carrier mobility . The electronic localization function (ELF) maps are also measured to map the likelihood of finding an electron between neighborhood atoms, which gives a better understanding of carrier migration.…”

The Effect of Nitrogen Incorporation on the Optical Properties of Si-Rich a-SiCx Films Deposited by VHF PECVD

“…The incorporation of different atoms into the materials from the working gas is a well-known process affecting the structure and physical properties of the materials [21][22][23][24]. In the previous work of our research group, by incorporating O atoms into a-SiCx films from the oxygen gas flow with PECVD technique, the influence of O doping on the luminescence characteristics of a-SiCx films was studied, and a three-level model based on the luminescence center of a Si dangling bond was established [25]. The net gain coefficient of the film was observed under ultraviolet pumping.…”

Effect of Nitrogen Doping on the Photoluminescence of Amorphous Silicon Oxycarbide Films

“…In the recent reference, Gallis et al systematically studied the white photoluminescence (PL) dynamics from SiC x O y film, where the band tail states related to the Si−O−C and/or the Si−C bonds were suggested as the sources of the luminescence [11]. Recently, optical gain was demonstrated in a-SiC x O y under ultraviolet excitation, which was attributed to the formation of a three-level luminescence model with the intermediate level related to Si dangling bond (DB) defects radiative state [15]. Furthermore, an increase in C content in SiC x O y films can cause a strong light emission ranging from near-infrared to orange regions [15].…”

“…Recently, optical gain was demonstrated in a-SiC x O y under ultraviolet excitation, which was attributed to the formation of a three-level luminescence model with the intermediate level related to Si dangling bond (DB) defects radiative state [15]. Furthermore, an increase in C content in SiC x O y films can cause a strong light emission ranging from near-infrared to orange regions [15]. Although performance is enhanced in SiC x O y films, progress remains slow.…”