Amorphous silicon

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

In Situ Measurement of Solid Electrolyte Interphase Evolution on Silicon Anodes Using Atomic Force Microscopy

Abstract: In situ measurements of the growth of solid electrolyte interphase (SEI) layer on silicon and the lithiation-induced volume changes in silicon in lithium ion half-cells are reported. Thin film amorphous silicon electrodes are fabricated in a configuration that allows unambiguous separation of the total thickness change into contribution from SEI thickness and silicon volume change. Electrodes are assembled into a custom-designed electrochemical cell, which is integrated with an atomic force microscope. The electrodes are subjected to constant potential lithiation/delithiation at a sequence of potential values and the thickness measurements are made at each potential after equilibrium is reached. Experiments are carried out with two electrolytes—1.2 m lithium hexafluoro-phosphate (LiPF6) in ethylene carbonate (EC) and 1.2 m LiPF6 in propylene carbonate (PC)—to investigate the influence of electrolyte composition on SEI evolution. It is observed that SEI formation occurs predominantly during the first lithiation and the maximum SEI thickness is ≈17 and 10 nm respectively for EC and PC electrolytes. This study also presents the measured Si expansion ratio versus equilibrium potential and charge capacity versus equilibrium potential; both relationships display hysteresis, which is explained in terms of the stress–potential coupling in silicon.

A study of the effect of composition on the microstructural evolution of a–SixC1−x: H PECVD films: IR absorption and XPS characterizations

Abstract: Amorphous silicon carbide films (a–SixC1−x :H) deposited by the argon- or helium-diluted PECVD technique were studied as a function of their composition. Microstructural investigations were mainly achieved by means of FTIR and XPS techniques. Nuclear techniques were used to obtain precise information on the film hydrogen content. The Si–H IR-absorption band was deconvoluted in different monohydride and dihydride silicon environments. The existence of SiH2 bonds in the Si-rich composition was evidenced. From the analysis of the C–H and Si–H absorption bands it is shown that hydrogen atoms are preferentially bonded to carbon atoms. The deconvolution of the Si2p core level peak suggests that above a composition of x ∊ 0.5, the noncarburized (Si, Si, H) local environment contribution increases to the detriment of the hydrocarburized (Si, C, H) environments. From the evolution of the C1s peak, it can be deduced that there is a change in the carbon atom bonding states when the film composition is varied. These results are correlated and discussed in terms of the local bonding environments and their evolution with film composition.

MOS device structure and integration method

Abstract: This invention describes a new method for forming self-aligned silicide for application in MOSFET, and a new structure of MOSFET device featuring elevated source and drain, with the objectives of reducing silicide penetration into the source and drain junctions, of eliminating junction spikes, of obtaining smoother interface between the silicide and the silicon substrate, and of reducing the chance of bridging of the silicides on the gate and on the source and drain. The new structure is made by depositing an amorphous layer of silicon on a silicon substrate already patterned with field oxide, gate oxide, polysilicon gate, and silicon nitride spacer on the gate sidewalls. Novel oxide sidewall spacers are then created by first implanting nitrogen into the horizontal surface of the amorphous silicon layer and subsequently thermally oxidizing the part of the amorphous silicon on the vertical sidewalls that is not exposed to nitrogen implantation. A dopant implantation followed by an annealing at 600° C. in nitrogen converts the deposited silicon layer into elevated source and drains. A refractory metal, such as titanium is then deposited over the substrate and, upon rapid thermal annealing, reacts with the elevated source and drain polysilicon to form silicide without consuming the substrate silicon, and without ill effect on the source/drain junctions in the single crystalline silicon. The chance of silicide bridging is greatly reduced due to the special geometry of the novel sidewall oxide spacers.

Introduction to Thin Film Transistors: Physics and Technology of TFTs

Abstract: Introduction.- Semiconductor Device Physics for TFTs.- Insulated Gate Field Effect Transistors, IGFETs.- Active Matrix Flat Panel Displays.- Hydrogenated Amorphous Silicon TFT Technology and Architecture.- Hydrogenated Amorphous Silicon TFT Performance.- Poly-Si TFT Technology and Architecture.- Poly-Si TFT Performance.- Transparent Amorphous Oxide Semiconductor TFTs.- Organic TFTs.- TFTs on Flexible Substrates.- Source-Gated Transistors.

Performance enhancement of thin-film amorphous silicon solar cells with low cost nanodent plasmonic substrates

Abstract: Performance of thin film photovoltaics largely relies on photon absorption capability. Here, we introduce a novel substrate with patterned aluminum nanodent arrays with unique light management capability. Hydrogenated amorphous silicon thin film solar cells have been fabricated on the nano-texturized substrate for optical property study and photovoltaic performance evaluation. Our measurements have shown significant enhancement on broadband light absorption using these patterned substrates via both geometrical light trapping and plasmonic coupling. Particularly, the enhancement factor reaches as high as 5–30 times at wavelength near the band edge. Numerical simulations confirm the measurements and uncover the mechanisms of the enhancement. More importantly, photovoltaic measurements on nanodent solar cells present improvements of over 31% and 27% in short circuit current and energy conversion efficiency respectively compared with planar solar cells. Therefore, the novel patterned substrates are promising candidates for low cost and high performance thin film solar cells.