Stoichiometry detuned silicon carbide as an orange and white light band solid-state phosphor

Abstract

A broadband orange and white light band solid-state phosphor from stoichiometry detuned amorphous silicon carbide (a-Si_xC_1−x) films with buried SiC and Si nanocrystals (SiC- and Si-ncs) is investigated. Such a semiconductor quantum dot embedded solid-state phosphor is synthesized by plasma-enhanced chemical vapor deposition with detuning of the fluence ratio g = [CH₄]/[SiH₄]. To modify its emitting color, the a-Si_xC_1−x films are grown with g = 40 to g = 70% for detuning its composition ratio from 0.74 to 0.62. After annealing at 1100 °C, a significant Raman scattering peak at 510 cm⁻¹ confirms the self-aggregation of Si-ncs with average sizes around 4.2 ± 0.5 nm, and the other two intensive transverse and longitude optical mode Raman scattering peaks at 744 and 933 cm⁻¹ verify the existence of nano-scaled 3C-SiC-ncs with the grain size reduced to 2.4 ± 0.3 nm after annealing. Under a gallium nitride laser diode illumination, the 3C-SiC-nc and Si-nc co-embedded a-Si_xC_1−x based solid-state phosphor grown at g = 60% and annealed at 1100 °C can provide intense orange or white-light emissions with a broadened linewidth of 200 nm. The emission centered at 485 nm is contributed by the self-trapped excitons surrounded at 3C-SiC-nc surface, whereas another emission peak at 580 nm is due to the quantum confined Si-ncs.

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Introduction

Silicon-rich silicon dioxide^1–5 and silicon nitride^6–10 have been employed as the potential matrices to synthesize and host Si nanocrystals (ncs) or quantum-dots (QDs) with strong quantum confinement effect. Nevertheless, the semi-insulating property of the aforementioned materials often provides a poor carrier transport mechanism when utilizing it as the active layer of the Si-QD based electroluminescent emitters.^11–20 When considering other alternative candidates for the host matrix of Si-ncs or Si-QDs, the large-area amorphous silicon carbide (a-Si_xC_1−x) film grown by low-temperature plasma-enhanced chemical vapor deposition (PECVD) with gaseous mixtures of silane (SiH₄) or disilane (Si₂H₆) with C_xH_y (CH₄, C₂H₄, C₂H₂, C₂H₆, C₃H₈, and C₄H₁₀) has been shown as a solution for decades.^21–23 Synthesizing the a-Si_xC_1−x at a low-power regime facilitates the dissociation of more SiH₄ than methane (CH₄) molecules with an appropriate setting of RF plasma power density so as to avoid the pre-decomposition of CH₄.²⁴ In addition, the low-defect and robust a-Si_xC_1−x films can be realized from a sample gaseous mixture of SiH₄ and CH₄. Previously, the SiC-ncs have been synthesized by several methods such as implantation of carbon ions into crystal Si wafers,²⁵ Si and C co-implantation into thermal SiO₂ films,²⁶ and annealing C₆₀ clusters coupled on porous Si.²⁷ Nevertheless, the Si_xC_1−x formation is generally localized in a complicated host matrix, which cannot provide bright luminescence without quantum confinement. Zhu et al. preliminarily demonstrated the porous cubic SiC (PCSC) via highly catalyzed electrochemical etching of polycrystalline 3C-SiC wafers in hydrogen fluoride ethanol solution to provide significant photoluminescence (PL) under illumination with a halogen lamp. The suspensions of 3C-SiC-ncs with diameters ranging from 1 to 6 nm are achieved by ultrasonic treatment on the PCSC reveals stable and strong blue PL emission.²⁸ During past decades, the Si-rich Si_xC_1−x films with buried Si-ncs has also emerged to enhance the luminescence under strong quantum confinement effect. Wang et al. suggested that the PL peak at 430 nm (3.0 eV) is likely induced by SiC nanoparticles, and another peak centered at 600 nm is related to band-to-band recombination in Si nanocluster.²⁹ Song et al. proposed the precipitation of Si-ncs and SiC-ncs in magnetron co-sputtered Si_xC_1−x matrix with detuning C/Si composition ratios and annealing parameters.³⁰ However, the evolution on precipitation and agglomeration of SiC-ncs and Si-ncs in a-Si_xC_1−x films after annealing treatment has yet to be detailed.³¹ To understand these phenomena in this work, the effect of annealing temperature on the structural and optical properties of the a-Si_xC_1−x with self-assembled SiC-ncs and Si-ncs after annealing is characterized by Raman scattering, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, Fourier transform infrared absorption spectroscopy (FTIR), and photoluminescence. In comparison with previous reports, this work emphasizes on characterizing the a-Si_xC_1−x films grown by adjusting fluence ratio of CH₄/SiH₄ gaseous mixture precursor under argon (Ar) dilution. In addition to the observation on composition, structural phase, crystallinity and bonding transformations in a-Si_xC_1−x films with buried 3C-SiC-ncs and Si-ncs with XPS, Raman, XRD and FTIR analyses, the enhanced PL of the annealed a-Si_xC_1−x films with varied compositions are reported.

Experimental section

Fabrication and measurement of Si_xC_1−x film

The low-temperature PECVD system with Ar diluted SiH₄ and CH₄ was employed to synthesize the a-Si_xC_1−x films on p-type (100)-oriented Si wafer pre-treated by dipping in buffered oxide etchant for 5 min for removing residual surface oxide layer. The RF power and substrate temperature were set as 20 W (50 mW cm⁻²) and 600 °C, respectively. The fluence ratio defined as g = CH₄/(SiH₄ + CH₄ + Ar) is varied from 70% to 40% at a decrement of 10 when the gas flow of SiH₄ was fixed as 65 sccm. The dissociation energy of CH₄ and SiH₄ are 416 and 323 kJ mol⁻¹, respectively. The samples synthesized with g ranging from 70% to 40% were annealed at 1100 °C for 90 min. The Raman scattering spectra were measured by using Nd:YAG laser at central wavelength of 532 nm as a light source to achieve the surface analysis. In the beginning, the system was calibrated with a single crystal Si wafer, which shows a significant standard peak at around 520 cm⁻¹. The crystallinity of the annealed samples was determined by grazing incidence XRD using Cu K_α radiation source with λ = 1.540562 Å. The FTIR (Thermo Nicolet NEXUS470) spectroscopy was performed by using a mercury cadmium tellurium/B sensor, which determines the bonding geometries in a-Si_xC_1−x network after averaging 32-time scans with a linewidth resolution of 4 cm⁻¹. The room-temperature PL of the all as-grown and annealed samples was performed by using a GaN laser diode with an average power of 30 mW at 405 nm. The PL ranged from 400 to 900 nm can be resolved by a monochromator using a 3000 groove per mm grating. To quantitatively compare the PL intensity, the working distance between the focusing lens and the sample was fine-tuned to maximize the PL intensity. During XPS analysis for diagnosing composition ratio, the a-Si_xC_1−x sample was excited by Mg K_α line at 1253.6 eV, and the Si_2p, C_1s, O_1s orbital electrons were emitted and detected from the sample surface at a vacuum of 10⁻⁶ torr.

Results and discussion

To achieve the phase transformation of a-Si_xC_1−x with the precipitation of SiC-ncs and Si-ncs, the fluence ratio is detuned and a subsequent annealing treatment at 1100 °C for 90 min is employed. The photographs of the Si_xC_1−x films grown at fluence ratios increased from g = 40% to g = 70% are shown in Fig. 1.

Fig. 1 Photographs of the Si_xC_1−x films grown at fluence ratios of g = (a) 40%, (b) 50%, (c) 60%, and (d) 70%.

The Raman, XRD, and FTIR analyses characterize the structural features, crystal transformation and bonding geometries. As shown in Fig. 2(a), the broadened Raman scattering band at 470 cm⁻¹ in as-grown and 1100 °C annealed samples are attributed to the transverse optical (TO) mode of amorphous Si (a-Si) in a-Si_xC_1−x matrix.³² A significant Raman scattering peak at 510 cm⁻¹ is shown to confirm the existence of Si-ncs after annealing, the wavenumber is red-shifted as compared to that of bulk Si at 520 cm⁻¹ due to the reduced grain size of Si-ncs. Previously, Zi et al. proposed that such a red-shifted Raman scattering peak from 520 cm⁻¹ to 508 cm⁻¹ is mainly attributed to the agglomeration of Si-ncs.³³ On the other hand, the other two intensive Raman scattering peaks at 744 cm⁻¹ and 933 cm⁻¹ are also observed, which are also deviated from the typical Raman scattering peaks of 3C-SiC bulk at 796 (for TO-phonon mode) and 972 cm⁻¹ (for longitudinal optical-phonon (LO-phonon) mode) after annealing at 1100 °C, as reported by Steckl et al.³⁴ Accordingly, the redshift of these 3C-SiC related Raman scattering peaks from 796 to 744 cm⁻¹ for TO phonon mode and 972 to 933 cm⁻¹ for LO phonon mode clearly indicates that the grain size of nano-scale 3C-SiC is relatively small as the 3C-SiC-ncs are formed after thermal annealing. With a fluence ratio of smaller than 50% during synthesis, the intensities of Raman scattering peaks related to the Si-ncs, the TO and LO modes of the 3C-SiC in the a-Si_xC_1−x sample are much weaker than those of the annealed Si_xC_1−x sample grown with g = 60%. This phenomenon is due to the insufficient SiC phase transformation and the enlarged grain of excess Si content, indicating that neither SiC-ncs nor Si-ncs can be self-aggregated in the a-Si_xC_1−x synthesized with g <50% to provide sufficiently large PL intensity.

Fig. 2 (a) The Raman scattering spectra and (b) the XRD rocking curves of as-grown and annealed a-Si_xC_1−x samples grown at substrate temperature of 600 °C (and annealed at 1100 °C for 90 minutes) with varying g from 70% to 40%.

Fig. 2(b) shows the XRD spectra of a-Si_xC_1−x samples synthesized with g = 60% without and with annealing at 1100 °C for 90 min. In comparison with as-grown sample, a stronger and narrower diffraction peak emerged at 2θ = 28.5° assigned to the (111)-oriented crystalline plane of Si is observed after annealing, as also confirmed by the Raman scattering result owing to transformation from nano-scale Si-ncs to micro-grain Si. Santoni et al. and Song et al. also reported the diffraction peak at ∼28.5° and ∼35.6° belong to the crystalline Si and 3C-SiC at (111) orientations, respectively.^30,35 Other relative peaks at 47.3° and 56.1° related to (220)-oriented and (311)-oriented Si, resepctively,³⁵ and those at 59.9° and 71.7° corresponding to the (220)-oriented and (311)-oriented 3C-SiC, respectively, are less significant.³⁵ In comparison with the results contributed by Santoni et al., the full width at maximum (FWHM) of (111)-oriented Si related diffraction peak becomes much narrower and stronger due to the Si-nc precipitation after annealing; however, the FWHM of (111)-oriented 3C-SiC related diffraction peak is somewhat wider than others owing to the aggregation of smaller 3C-SiC-ncs.³⁵ The estimated nano-grain size³⁶ of Si-ncs and SiC-ncs are approximately 4.2 ± 0.5 nm and 2.4 ± 0.3 nm, respectively. Thermal annealing treatment at 1100 °C facilitates to improve crystallinity and favors the formation of Si-ncs and 3C-SiC-ncs in a-Si_xC_1−x films.

In Fig. 3(a) and (b), owing to the insufficient RF power for the CH₄ dissociation when growing the a-Si_xC_1−x at g = 70%, the FTIR analysis provide the evidence of weak broadband C–H stretching mode in CH₂ and CH₃ bonds at 2840–2980 cm⁻¹ that is in good agreement with the report given by Tawada et al.³⁷ The FTIR peak at 2190 cm⁻¹ corresponding to Si–H₃ stretching mode³⁸ is also observed from all a-Si_xC_1−x samples synthesized at g = 40%–70%, whereas the FTIR peaks at 1250 and 1150 cm⁻¹ are attributed to Si–CH₃ stretching and Si–O–C signals,³⁹ respectively. A distinct band at 792–806 cm⁻¹ assigned to Si–C stretching mode is also found in as-grown samples.⁴⁰ The absorbance of Si–O–C is increased clearly at sample grown with g = 70% as it is easier oxidized.

Fig. 3 The broadband FTIR spectra of (a) as-grown and (b) annealed a-Si_xC_1−x films with decreasing fluence ratios g from 70% to 40%.

The peak centered at 2096 cm⁻¹ arises from Si–H stretching and the Si–H₃ stretching at 2180 cm⁻¹ is transformed into Si–H stretching mode after annealing at 1100 °C because the hydrogen bond is broken up to diffuse out, as shown in Fig. 4(a). Accordingly, Si-ncs can be easier aggregated by dehydrogenation of Si–H₃ at high temperature. Ma et al.⁴¹ suggests that the Si-H_n related FTIR signals disappear after thermal annealing when the dehydrogenation phenomenon facilitates to break up the Si–H bond and precipitate Si-ncs. As shown in Fig. 4(b), the Si–C stretching peak is blue-shifted from 792 to 802 cm⁻¹ so as to make the Si–C bond strength stronger than others. In addition, the Si–C stretching peak is blue-shifted from 737 cm⁻¹ to 800 cm⁻¹ with increasing annealing temperature from 800 to 1100 °C due to the production of SiC-ncs, as reported by Song et al.³⁰ The bonding geometries between Si–Si and Si–C network are gradually transformed to produce shorter bond lengths at g = 60%, thus providing the narrower FWHM of Si–C stretching mode when comparing with the sample at as-grown condition.

Fig. 4 Zoom-in FTIR absorption spectra reveal (a) a transfer from Si–H₃ stretching (top) into Si–H stretching (down) mode in the a-Si_xC_1−x after thermal annealing at 1100 °C for 90 minutes, and (b) Si–C stretching modes in as-grown (top) and annealed a-Si_xC_1−x samples (down).

Detuning Si-rich condition or not can be completely realized by alternating the g ratio. With the XPS analysis on the binding energies and counts of the photoelectrons at various core orbits in Si and C atoms, the composition ratio x and nonstoichiometry of a-Si_xC_1−x can be verified, respectively. As shown in Fig. 5(a)–(d), with varying fluence ratios from 40 to 70%, the Si concentration is reduced from 70.9 to 58.6% and the C concentration is increased from 25.5 to 36.7%. In Fig. 6, the Si/C composition ratio of a-Si_xC_1−x film is 2.78, 2.24, 1.99, and 1.6, corresponding to the composition ratio x of a-Si_xC_1−x is 0.74, 0.69, 0.67 and 0.62 when growing the a-Si_xC_1−x with the fluence ratio g of 40%, 50%, 60%, and 70%, respectively.

Fig. 5 Broad-scan XPS spectra of a-Si_xC_1−x films grown at fluence ratio g of (a) 40%, (b) 50%, (c) 60% and (d) 70%.

Fig. 6 Composition ratio Si/C and molar ratio x in a-Si_xC_1−x films as a function of fluence ratio.

Additionally, in Fig. 7(a)–(d) and 8(a)–(d), the Si_2p and C_1s core level electron related XPS peaks are fitted to corroborate what bond and constituent in Si_xC_1−x film can be formed, such as the energies of 100.3–100.9 eV and 99.5–99.8 eV for Si–C and Si–Si bond in Si_2p level, respectively, and 283.1–283.4 eV, 284.8 eV and 285.4 eV for C–Si, C–C_sp² and C–C_sp³ in C_1s level, respectively.^35,42,43 As shown in Fig. 7(a)–(d) from fitting results of Fig. 5(a)–(d), the Si–C bonding rate is decreased with increasing g from 40 to 50% by analyzing the Si_2p core level dependent orbital electrons. By increasing the fluence ratio from 60% to 70%, the Fig. 9(a) reveals that the Si–C bonding rate analyzed by the related FTIR peak turns from increasing to decreasing trend.

Fig. 7 Experimental (black line) and fitted curves (Si–Si, Si–C, C–Si–O and Si–O components) of Si_2p orbital electron related XPS spectra for a-Si_xC_1−x grown at g of (a) 40%, (b) 50%, (c) 60% and (d) 70%.

Fig. 8 Experimental (black line) and fitted curves (C–Si, C–C_sp² and C–C_sp³ components) of C_1s orbital electron related XPS spectra for a-Si_xC_1−x grown at g of (a) 40%, (b) 50%, (c) 60% and (d) 70%.

Fig. 9 (a) Si_2p orbital electron related XPS intensities of Si–Si and Si–C bonds for a-Si_xC_1−x grown at different fluence ratios. (b) C_1s orbital electron related XPS intensities of C–Si bond for a-Si_xC_1−x grown at different fluence ratios.

In Fig. 9(a), it is also observed that the Si–Si bonding rate monotonically decreases with enlarging fluence ratio g from 40% to 70%. On the other hand, the analysis of C_1s core level related electrons confirms that the C–Si bonding rate increases by growing the a-Si_xC_1−x at g = 60%, as shown in Fig. 8(a)–(d) from the fitted results of Fig. 5(a)–(d). Therefore, more precipitated SiC-ncs are found when synthesizing the a-Si_xC_1−x at g = 60%, as the enhanced Si–C bonding rate is confirmed via the enlarged Si–C components in the XPS spectra of Si_2p and C_1s core level electrons (see Fig. 9(b)). This deposition recipe is critical as it creates large quantities of Si-ncs and SiC-ncs at sufficiently enriched but not too excessive Si environment. As the formation of Si-ncs is determined how much Si atoms can be agglomerated, the PL is reduced accordingly due to over enriched Si excess condition which forms extremely large Si micro-grains such that the quantum confinement effect is diminished. As a result, the most intense PL signal with dense SiC-ncs and Si-ncs are obtained in Si_xC_1−x films with composition ratio x of 0.67. In view of previous works, Santoni et al.³⁴ also verified the presence of a consistent Si polycrystalline phase which coexists with the polycrystalline 3C-SiC in laser-irradiated Si_xC_1−x samples at a composition ratio of x = 0.67. In other words, the best growth condition to induce plentiful Si-ncs and SiC-ncs is determined at the composition ratio of x = 0.67 in the Si-rich Si_0.67C_0.33 films.

In addition, the SEM micrographs of a-Si_xC_1−x films deposited with fluence ratio increasing from 40% to 70% at a growth temperature of 600 °C are performed in Fig. 10(a)–(d). The deposited thicknesses of the a-Si_xC_1−x films synthesized at various fluence ratios from 40% to 70% at an increment of 10% are linearly reduced from 450 to 321 nm under same deposition duration. With increasing the CH₄/SiH₄ fluence ratio, the deposition rate is decreased from 15 to 10.7 nm min⁻¹ owing to the deposition of reduced amount of excess Si atoms, as shown in Fig. 10(e). The number of Si–C bond is increased to make the a-Si_xC_1−x film thinner with larger fluence ratio as the bond length of Si–C (1.87 Å) is shorter than that of Si–Si bond (2.35 Å); however, the number of Si–C bond is decreased suddenly when synthesizing at g = 70% to result in an abrupt shrinkage on the thickness of the nearly stoichiometric SiC film. As a result, the PL patterns of the annealed a-Si_xC_1−x samples change light colors from orange to nearly white when enlarging the fluence ratio from g = 40% to g = 70%, as shown in Fig. 11(a). Fig. 11(b) shows the PL spectra of the as-grown and annealed Si-rich Si_xC_1−x samples. The intense visible PL centered at 485 nm is found in annealed sample of g = 60%, which is mainly attributed to the broadband luminescence from SiC-ncs.

Fig. 10 The SEM micrographs of a-Si_xC_1−x films at fluence ratios of (a) 40%, (b) 50%, (c) 60% and (d) 70%. (e) Deposition rate of a-Si_xC_1−x film as a function of fluence ratio.

Fig. 11 (a) Images: the corresponding PL patterns of the annealed Si_xC_1−x films grown at fluence ratios increased from g = 40% to g = 70% (from left to right). Data (b) PL spectra of as-grown and annealed a-Si_xC_1−x films grown with fluence ratio increased from g = 40% to g = 70%. (c) The peak PL intensities fitted by two Gaussian components at 485 and 580 nm for annealed a-Si_xC_1−x grown at g = 60% (top), g = 50% (middle) and g = 40% (bottom).

When serving as a solid-state phosphor under the illumination with a gallium nitride (GaN) laser diode, such a bright white-light emission at 485 nm emerges from the edge recombination of carriers in SiC-ncs is provided by self-trapped excitons at the surface states between SiC-ncs and surrounding matrix. Zhu et al.²⁸ also corroborates that the stronger PL peak centered at 475 nm is contributed by the band to band carrier recombination in 3C-SiC-ncs under excitation at 400 nm. In addition, the secondary PL peak centered at 580 nm is also observed due to the contribution of Si-ncs. In a previous work, Löper et al. suggested that the PL peak at 610 nm is the strongest luminescence due to the formation of Si-ncs within Si_xC_1−x matrix.⁴⁴ As shown in fitting results of Fig. 11(c) from (b), with the fluence ratio g decreasing from 60% to 40%, the normalized PL intensities centered at 485 nm (contributed by SiC-ncs with D_SiC-nc = 2.4 ± 0.3 nm) and 580 nm (contributed by Si-ncs with D_Si-nc = 4.2 ± 0.5 nm) are significantly attenuated from 134 to 36 (count per nm) and from 78 to 31 (count per nm), respectively, as the insufficient C atoms fails to precipitate more SiC-ncs and the over-excessive Si atoms inevitably form Si micro-grains. The similar Si-nc diameter corresponding to the 580 nm PL can also be calculated as 2.55 nm by using Delerue's empirical formula.^45,46 According to fitting results from Fig. 11(c), the variation of PL intensities of SiC-ncs and Si-ncs as a function of fluence ratio is shown in Fig. 12(a). In comparison with the PL of a-Si_xC_1−x samples synthesized at g ranged from 60 to 40%, enlarging the fluence ratio to 70% inevitably weakens the PL emission owing to the formation of nearly stoichiometric SiC, whereas the Si-ncs overgrows to form micro-grain and the quantum confined emission weakens accordingly. From Fig. 12(b), the PL remains unchanged peak wavelengths but varies relative powers in view of variation of SiC-ncs and Si-ncs densities. Among all conditions, the largest PL is observed when growing the a-Si_xC_1−x at g = 60% as the optimized precipitation of SiC-ncs and Si-ncs can be approached in this sample after post-annealing. With blue-light illumination, the 3C-SiC-nc and Si-nc co-embedded a-Si_xC_1−x based solid-state phosphor effectively provides intense phosphorus light emissions with orange or white color covering a broadened tunable linewidth of up to 200 nm. In the future, such a band-engineered a-SiC solid-state phosphor could easily find its potential role in monolithically integrating with semiconductor light-emitting or laser devices for white-lighting applications.⁴⁷

Fig. 12 (a) The SiC-ncs and Si-ncs (annealed and as-grown) related PL intensities at 485 and 580 nm as a function of fluence ratio g under annealing treatment at 1100 °C for 90 minutes. (b) The PL peak wavelengths of SiC-ncs and Si-ncs (annealed) as a function of fluence ratio g under 1100 °C annealing treatment for 90 minutes.

Conclusion

A stoichiometry detuned a-Si_xC_1−x synthesized by PECVD with varying fluence ratio (g) is demonstrated to serve as the orange or white light band-engineered solid-state phosphor for potential lighting applications. The molar ratio x of a-Si_xC_1−x can be adjusted from 0.74 to 0.62 by alternating g from 40% to 70%, providing the optimized formation of plentiful Si-ncs and 3C-SiC-ncs co-existed in Si-rich Si_0.67C_0.33 film at g = 60%, as confirmed by observing three prominent Raman scattering peaks at 510, 744 and 933 cm⁻¹ after 1100 °C. Distinguished XRD peaks at 28.5 and 35.6° verify the crystallization of (111)-oriented Si and (111)-oriented 3C-SiC nano-scaled grains with average grain sizes of 4.2 ± 0.5 nm (for Si-ncs) and 2.4 ± 0.3 nm (for 3C-SiC-ncs), respectively. For a-Si_xC_1−x film grown at g of 60%, the Si–C related FTIR peak is blue-shifted from 792 to 802 cm⁻¹ when the Si–C bond strengthens to facilitate the precipitation of 3C-SiC-ncs. Under illumination with a GaN laser diode, the brightest light emission centered at 485 nm from annealed a-Si_xC_1−x grown with g = 60% at 1100 °C for 90 min is observed, which is attributed to the intense radiative recombination of self-trapped excitons at surface states of 3C-SiC-ncs. Another PL peak at 580 nm is contributed by luminescent Si-ncs under strong quantum confinement. Enlarging the fluence ratio to 70% suddenly diminishes the PL emission owing to the formation of nearly stoichiometric SiC film, wherein the Si-ncs overgrows to form micro-grain and the quantum confined emission weakens accordingly. The 3C-SiC-nc and Si-nc co-embedded a-Si_xC_1−x can serve as the solid-state phosphor to effectively provide intense phosphorus light emissions with orange or white color covering a broadened tunable linewidth of up to 200 nm.

Acknowledgements

The authors thank the Ministry of Science and Technology, Taiwan, R.O.C., for financially supporting this research under grants MOST 103-2221-E002-042-MY3 and MOST-104-2221-E-002-117-MY3.

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