Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon

Slama, Sonia Ben; Hajji, M.; Ezzaouia, Hatem

doi:10.1186/1556-276x-7-464

Cited by 16 publications

(10 citation statements)

References 12 publications

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“…crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22]. Figure 3 shows the reflectance spectra for the as-deposited, furnace annealed at 650 °C and flash lamp annealed samples, respectively.…”

Section: Optical Propertiessupporting

confidence: 79%

“…The top layer-2 was treated as a Bruggeman's EMA for poly-Si and void mixture, where poly-Si was fitted using Tauc-Lorentz and Gasussian oscillators. The optical model resulted an excellent fit to the experimental psi and delta curve obtained from SE measurements as can be seen crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22]. Figure 3 shows the reflectance spectra for the as-deposited, furnace annealed at 650 °C and flash lamp annealed samples, respectively.…”

Section: Optical Propertiessupporting

confidence: 76%

“…A direct evidence of crystallization of the a-Si films was that a new characteristic peak around 280 nm in the UV region of the reflectance spectra appeared for the films annealed at temperatures above 550 • C. The characteristic peak around~280 nm represents reflection band, which can be explained by the optical transitions near the direct band gap [20]. This characteristic peak of crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22].…”

Section: Optical Propertiessupporting

confidence: 74%

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Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

et al. 2018

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Low-temperature growth of microcrystalline silicon (mc-Si) is attractive for many optoelectronic device applications. This paper reports a detailed comparison of optical properties, microstructure, and morphology of amorphous silicon (a-Si) thin films crystallized by furnace annealing and flash lamp annealing (FLA) at temperatures below the softening point of glass substrate. The initial a-Si films were grown by plasma enhanced chemical vapor deposition (PECVD). Reflectance measurement indicated characteristic peak in the UV region~280 nm for the furnace annealed (>550 • C) and flash lamp annealed films, which provided evidence of crystallization. The film surface roughness increased with increasing the annealing temperature as well as after the flash lamp annealing. X-ray diffraction (XRD) measurement indicated that the as-deposited samples were purely amorphous and after furnace crystallization, the crystallites tended to align in one single direction (202) with uniform size that increased with the annealing temperature. On the other hand, the flash lamp crystalized films had randomly oriented crystallites with different sizes. Raman spectroscopy showed the crystalline volume fraction of 23.5%, 47.3%, and 61.3% for the samples annealed at 550 • C, 650 • C, and with flash lamp, respectively. The flash lamp annealed film was better crystallized with rougher surface compared to furnace annealed ones.

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Section: Optical Propertiessupporting

confidence: 79%

Section: Optical Propertiessupporting

confidence: 76%

Section: Optical Propertiessupporting

confidence: 74%

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Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

et al. 2018

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“…However, the process to thermally grow SiO 2 , despite having a small effect on the structure when applied to c -Si, has a limitation when applied to PS nanostructures that have an aspect ratio as high as 400:1 [ 22 ]. The high operating temperature of thermal SiO 2 deposition at 400–1100 °C [ 11 , 12 ] will damage the nano-porous layer [ 23 ]. Therefore, the method to deposit an oxide passivation layer on nanostructured Si must be designed in such a way that it can precisely control the thickness of the oxide to prevent a complete oxidation, while the processing temperature must be low enough to preserve the original nanostructure.…”

Section: Introductionmentioning

confidence: 99%

Nanostructure of Porous Si and Anodic SiO2 Surface Passivation for Improved Efficiency Porous Si Solar Cells

et al. 2021

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The photovoltaic effect in the anodic formation of silicon dioxide (SiO2) on porous silicon (PS) surfaces was investigated toward developing a potential passivation technique to achieve high efficiency nanostructured Si solar cells. The PS layers were prepared by electrochemical anodization in hydrofluoric acid (HF) containing electrolyte. An anodic SiO2 layer was formed on the PS surface via a bottom-up anodization mechanism in HCl/H2O solution at room temperature. The thickness of the oxide layer for surface passivation was precisely controlled by adjusting the anodizing current density and the passivation time, for optimal oxidation on the PS layer while maintaining its original nanostructure. HRTEM characterization of the microstructure of the PS layer confirms an atomic lattice matching at the PS/Si interface. The dependence of photovoltaic performance, series resistance, and shunt resistance on passivation time was examined. Due to sufficient passivation on the PS surface, a sample with anodization duration of 30 s achieved the best conversion efficiency of 10.7%. The external quantum efficiency (EQE) and internal quantum efficiency (IQE) indicate a significant decrease in reflectivity due to the PS anti-reflection property and indicate superior performance due to SiO2 surface passivation. In conclusion, the surface of PS solar cells could be successfully passivated by electrochemical anodization.

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“…Conventional approaches include crystallization of a-Si films through laser annealing and high-temperature (600-1000 ºC) vacuum annealing [8,9]. Laser annealing, commercially known as low temperature poly silicon (LTPS), is accomplished by scanning a laser beam across the a-Si film surface [10,11].…”

Section: Introductionmentioning

confidence: 99%

Microcrystalline Si thin films by re-crystallization of electrophoretic deposited Si nanoparticle films

et al. 2014

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A new route to producing microcrystalline silicon (µc-Si) thin films by re-crystallizing Si nanoparticle films by flash lamp method is presented. High quality Si nanoparticle films with high uniformity and high particle packing density were obtained using a stable non-aqueous Si nanoparticle suspension and the electrophoretic deposition (EPD) method. Morphology and crystallinity of as-deposited and flash lamp re-crystallized Si nanoparticle films were studied. INTRODUCTIONSi nanoparticles are increasing in interest recently for their high surface area to volume ratio, quantum properties, and re-crystallization potential. Promising applications of Si nanoparticle films include Li ion battery electrode [1], spontaneous hydrogen generation [2], photon downshifting for solid state lighting [3] and solar cells [4], quantum energy devices [5], and re-crystallized µc-Si. The latter is the present focus area. Among a variety of applications, µc -Si thin film is the critical material that leads to advanced flat panel displays with superior performance and high-efficiency solar cells with low-cost [6,7]. Flat panel liquid crystal displays with µc-Si thin film transistors (TFTs) achieve higher display brightness and faster dynamic response while consuming less power compared to amorphous Si (a-Si) TFTs due to higher carrier mobility, better stability and lower recombination loss. Multi-junction thin film Si solar cells use µc-Si as bottom sub-cells to absorb red and infrared light and improve the stability and efficiency of the solar cell. Commercial grade µc-Si films have high uniformity in terms of thickness, composition, and structure. Further, low-cost devices require high deposition rates of µc-Si for high throughput and low processing temperatures to use inexpensive substrates, such as glass and polymers.There is currently no efficient method to produce large area µc-Si thin films at low temperatures. Conventional approaches include crystallization of a-Si films through laser annealing and high-temperature (600-1000 ºC) vacuum annealing [8,9]. Laser annealing, commercially known as low temperature poly silicon (LTPS), is accomplished by scanning a laser beam across the a-Si film surface [10,11]. This process is very slow and accounts for 80% loss of yield compared to conventional a-Si TFT [12]. Laser annealing is especially not suitable for large area devices, such as solar panels and TV screens. High-temperature vacuum annealing is not suitable for common substrate materials, e.g. glass and polymers, and is also not economic. Although recently there have been efforts using flash lamp to crystallize a-Si films [13,14], the resulting crystal size is relatively small (< 0.5 μm, on the same order as laser annealing) due to fundamental thermodynamic limitations.This paper presents progress of a new method to produce µc-Si films by flash lamp recrystallization of densely packed Si nanoparticle films, as illustrated in Figure 1. Objectives include (1) developing a stable Si nanoparticle suspension, (2) depositing high quali...

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Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon

Cited by 16 publications

References 12 publications

Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

Nanostructure of Porous Si and Anodic SiO2 Surface Passivation for Improved Efficiency Porous Si Solar Cells

Microcrystalline Si thin films by re-crystallization of electrophoretic deposited Si nanoparticle films

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