Structural and Optical Properties of Luminescent Silicon Carbonitride Thin Films

Khatami, Zahra; Wilson, Patrick; Taggart, Owen; Frisina, Dan R; Wójcik, J.; Mascher, P.

doi:10.1149/06105.0097ecst

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…Slight variation in the gas flow rate of CH 4 influences the film composition significantly compared to diluted N 2 and SiH 4 gas sources and gives a wide range of control of film composition. In addition, the PL properties of SiN fabricated using the aforementioned ECR PECVD system has been previously investigated [14,26]. Previously, to explore the influence of substrate temperature, four thin films were fabricated using identical parameters except for the deposition temperature (SiCN samples), where we investigated the variation of the film composition and electronic structure of a subset of samples in terms of the chemistry of the plasma and the species arriving on the growing surface at different deposition temperatures [15].…”

Section: Sample Setsmentioning

confidence: 99%

“…We previously investigated the optical properties of SiCN thin films in terms of the variation of precursors; e.g. CH 4 [13], N 2 [14] and Ar [15], post-thermal annealing [16], substrate temperatures and changes of the plasma chemistry, doping with rare earth ions [17], and we recently suggested a luminescence model for such materials for the first time [18]. The hardness of nanocomposites considerably exceeds the hardness of their bulk components [19], which is well aligned with the current path of silicon photonics technology, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films

2019

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Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films were grown using electron cyclotron resonance chemical vapour deposition using a mixture of methane, nitrogen, and silane as precursors. The origin of the variation of macroscopic properties such as hardness (H), elastic modulus (E), photoluminescence (PL), and the optical band gap was investigated through their correlation with the microscopic features of a-SiCN:H thin films as a function of the process parameters, including the deposition temperature and methane gas flow rate. From a microstructural perspective, the thin films were investigated using x-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, elastic recoil detection, transmission electron microscopy, and x-ray diffraction. It is verified that an increase of the substrate temperature resulted in the substitution of hydrogen atoms mainly by carbon atoms, causing the density of the silicon carbide-related structures to increase in the amorphous structure of the a-SiCN:H thin films. Hardness and elastic modulus were found to increase with the deposition temperature and decreased with an increase of the methane gas flow during the deposition, resulting in higher carbon content in the films. The observed changes are ascribed to the reduced density of the weak hydrogen terminated bonds and the variation of the relative bond density of Si–C to Si–N bonds. In addition, the thin films were depth profiled using a slow positron beam to investigate the role of vacancies. The observed increase of the positronium formation with increasing deposition temperature was found to correlate with the variation of PL, where an enhancement of the visible emission originating from carbon-related defects was observed. A set of optimized process parameters to fabricate a-SiCN:H thin films with improved visible emission and hardness properties is suggested.

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Section: Sample Setsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films

2019

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“…Understanding the interdependency of light emission properties and film composition and structure requires a comprehensive study. Previously, we explored the role of CH 4 and N 2 gas flow 2,21 and post-deposition thermal annealing on the PL emission, composition, and microstructure of a-SiC x N y :H z 22 and suggested the luminescence model for this ternary material. 23 However, a full understanding of the influence of the deposition conditions on the luminescence properties of SiC x N y thin films is still lacking.…”

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Influence of Deposition Conditions on the Characteristics of Luminescent Silicon Carbonitride Thin Films

Khatami

Bosco

Wójcik

et al. 2018

ECS J. Solid State Sci. Technol.

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The influence of the substrate temperature and argon gas flow on the compositional, structural, optical, and light emission properties of amorphous hydrogenated silicon carbonitride (a-SiC x N y :H) thin films were studied. Thin films were fabricated using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD) at a range of substrate temperatures from 120 to 170 • C (corresponding to deposition temperatures of 300 to 450 • C) in a mixture of SiH 4 , N 2 , and CH 4 precursors. Variable angle spectroscopic ellipsometer (VASE), elastic recoil detection (ERD), and Rutherford backscattering spectrometry (RBS) verified optical bandgap widening, layer densification, and an increase of the refractive index at higher substrate temperatures. The microstructure of a-SiC x N y :H z thin films was determined by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The substrate temperature strongly affected the binding state of all atoms, and in particular, carbon atoms attached to silicon and nitrogen, as well as hydrogen-terminated bonds. We correlated the films' microstructural changes to a higher species' mobility arriving on the growin layer at higher temperatures. Photoluminescence (PL) measurements showed that the total intensity of visible light emission increased. A systematic blueshift of the centroid of the wide PL peak was observed following the increase of optical gap. 2 This is a consequence of their unique properties inherited from the combined properties of binary substructures, silicon carbide (SiC), silicon nitride (SiN), and carbonitride (CN). On the one hand, the durability and hardness of SiN structures cannot compete with those of carbon-based hard counterparts such as diamond-like carbon (DLC), CN, and SiC materials.3 On the other hand, carbon-based films do not offer the required properties for current optical designs, 4 while SiN thin films have been considered as the basis for several optoelectronic devices. 5 The protective properties of SiC x N y materials appear as an intermediate matrix to meet the demands in hard coating technology and concurrently, the tunability of SiC x N y 's electrical and optical properties raises its interest in the field of Photonics. SiC x N y structures have appeal to researchers for wear-resistant 6 and corrosion-resistant coatings, 7 and recently, for silicon-based anode materials in lithium ion batteries. 8 In addition, SiC x N y structures are used for gate dielectrics in thin film transistors 9 and diffusion barriers.10 They appear to broaden the optical parameter space required for the application of ultraviolet (UV) detectors 11,12 and the passivation layer in the third generation "all-silicon" tandem solar cells. 13,14 To this end, Chen et al. reported a direct bandgap of 3.8 eV for c-Si 2 N 4 C 15 and Azam et al. 16 investigated the tunability of the bandgap depending on the dominant phase present in the SiC x N y layer. We previously showed that the visible photoluminescence (PL) emission from ...

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Annealing of silicon carbonitride nanostructured thin films: interdependency of hydrogen content, optical, and structural properties

et al. 2017

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Structural and Optical Properties of Luminescent Silicon Carbonitride Thin Films

Cited by 3 publications

References 14 publications

Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films

Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films

Influence of Deposition Conditions on the Characteristics of Luminescent Silicon Carbonitride Thin Films

Annealing of silicon carbonitride nanostructured thin films: interdependency of hydrogen content, optical, and structural properties

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