Amorphous silicon

About: Amorphous silicon is a research topic. Over the lifetime, 26777 publications have been published within this topic receiving 423234 citations.

Semiconductor electrode having improved grain structure and oxide growth properties

Abstract: The use of nitrogen doped amorphous silicon as an electrode material for a semiconductor integrated circuit is described. A preferred embodiment is a single transistor flash EPROM cell is disclosed having a tunnel dielectric (202), a floating gate (206), an intergate dielectric having three layers (208, 210, 212), and a control gate (218). The floating gate (206) is composed of in-situ nitrogen doped amorphous silicon. Due to the nitrogen doping the floating gate (206) retains its microcrystalline structure under high temperatures, eliminating large grain boundaries in the floating gate (206). As a result, arrays composed of the disclosed EPROM cell have improved memory cell threshold (V TM ) distributions. In addition, silicon oxide grown from the the floating gate (206) has fewer stress induced defects reducing leakage paths that contribute to data retention errors. An alternate embodiment uses nitrogen doped amorphous silicon as the capacitor plates (304 and 306) in a DRAM cell (300). The nitrogen doped amorphous silicon oxidizes at a slower rate than undoped amorphous silicon and has less inherent stress resulting in thinner a capacitor dielectric (308) of fewer defects. The capacitor plates (304 and 306) maintain their microcrystalline structure throughout subsequent temperature cycling resulting in increased capacitor area.

Hydrogenated Amorphous Silicon Alloy Deposition Processes

Abstract: Introduction material characteristics of amorphous silicon-based alloys film diagnostic measurements conventional glow discharge deposition processes for amorphous silicon-based alloys design of glow discharge deposition reactors glow discharge deposition parameters for hydrogenated amorphous silicon glow discharge deposition reaction chemistry for hydrogenated amorphous silicon modifications of conventional glow discharge remote-plasma-assisted chemical vapour deposition methods photochemical vapour deposition thermally-induced chemical vapour deposition physical vapour deposition methods etching properties of amorphous silicon-based alloys comparison of alternative deposition methods microcrystalline silicon and silicon carbide safety.

Design of Plasmonic Nanoparticles for Efficient Subwavelength Light Trapping in Thin-Film Solar Cells

Abstract: This paper explores geometry-sensitive scattering from plasmonic nanoparticles deposited on top of a thin-film amorphous silicon solar cell to enhance light trapping in the photo-active layer. Considering the nanoparticles as ideal spheroids, the broadband optical absorption by the silicon layer is analyzed and optimized with respect to the nanoparticle aspect ratio in both the cases of resonant (silver) and nonresonant (aluminum) plasmonic nanostructures. It is demonstrated how the coupling of sunlight with the semiconductor can be improved through tuning the nanoparticle shape in both the dipolar and multi-polar scattering regimes, as well as discussed how the native oxide shell formed on the nanospheroid surface after the prolonged action of air and moisture affects the light trapping in the active layer and changes the photocurrent generation by the solar cell.

Characterization and optimization of absorbing plasma-enhanced chemical vapor deposited antireflection coatings for silicon photovoltaics.

Abstract: We have optimized plasma-enhanced chemical vapor deposition (PECVD) of SiN-based antireflection (AR) coatings with special consideration for the short-wavelength (<600 nm) parasitic absorption in SiN. Spectroscopic ellipsometry was used to measure the dispersion relation for both the refractive index n and the extinction coefficient k, allowing a precise analysis of the trade-off between reflection and absorption in SiN-based AR coatings. Although we focus on photovoltaic applications, this study may be useful for photodetectors, IR optics, and any device for which it is essential to maximize the transmission of light into silicon. We designed and optimized various AR coatings for minimal average (spectrally) weighted reflectance (〈Rw〉) and average weighted absorptance (〈Aw〉), using the air mass 1.5 global solar spectrum. In most situations 〈Rw〉 decreased with higher n, but 〈Aw〉 increased because k increased with n. For the practical case of a single-layer AR coating for silicon under glass, an optimum refractive index of ∼2.23 (at 632.8 nm) was determined. Further simulations revealed that a double-layer SiN stack with an n = 2.42 film underneath an n = 2.03 film gives the minimum total photocurrent loss. Similar optimization of double-layer SiN/SiO2 coatings for silicon in air revealed an optimum of n = 2.28 for SiN. To determine the allowable tolerance in index and film thickness, we generated isotransmittance plots, which revealed more leeway for n values below the optimum than above because absorption begins to reduce photocurrent for high n values.