Amorphous silicon

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

Effects of Surface Morphology of Transparent Electrode on the Open-Circuit Voltage in a-Si:H Solar Cells

Abstract: The open-circuit voltage of hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells depends on the surface morphology of transparent electrodes and the i-layer thickness. We have studied the relationship between the Voc and these parameters experimentally. To investigate the detailed mechanism of the Voc drop, transmission and scanning electron microscopies (TEM and SEM) were used, and it was found by the TEM images that white stripelike defective regions were generated in the i-layer deposited on highly textured transparent electrodes. From the current-voltage characteristics of these solar cells under the dark condition, the relationship between the defects and the electrical properties of the cells has been studied. The results showed that the defect acts as a recombination center of carriers.

Plasma deposition of hydrogenated amorphous silicon: Studies of the growth surface

Abstract: This review focusses on the plasma-surface interactions and surface processes involved in a-Si: H thin film growth. We restrict our discussion of growth fluxes to a summary, and do not address plasma kinetics. In recent years, powerful in situ experiments have been carried out on the growing film surface, which reveal the adsorption, penetration, reaction, and elimination of precursor species, as well as the atomic-scale morphology and composition of the growth zone. Good data sets are available both for PACVD and reactive magnetron sputter deposition. These form an interesting comparison, since the former process is dominated by the hydrogen-rich radical SiH3 at low energy, and the latter by energetic atomic Si and H. We review the key experiments and conclusions, underlining those aspects which are well established and those which remain qualitative; and we discuss the transition from amorphous to fine-grained polycrystalline film growth at high hydrogen pressures in terms of the surface mechanisms. This field is now entering a scientific stage where a detailed theory of low-temperature, plasma-assisted growth can be developed.

Method for fabricating a semiconductor device using a catalyst introduction region

Abstract: Into an amorphous silicon film, catalyst elements for accelerating the crystallization are introduced. After patterning the amorphous silicon films in which the catalyst elements have been introduced into an island pattern, a heat treatment for the crystallization is conducted. Thus, the introduced catalyst elements efficiently diffuse only inside the island-patterned amorphous silicon films. As a result, a high-quality crystalline silicon film, having the crystal growth direction aligned in one direction and having no grain boundaries, is obtained. Using the thus formed crystalline silicon film, semiconductor devices having a high performance and stable characteristics are fabricated efficiently over the entire substrate, irrespective of the size of the devices.

a-Si:H TFTs made on polyimide foil by PE-CVD at 150 °C

Abstract: We have fabricated high-performance amorphous silicon thin-film transistors (a-Si:H TFTs) on 2 mil. (51 µm) thick polyimide foil substrates. The TFT structure was deposited by r.f.-excited plasma enhanced chemical vapor deposition (PECVD). All TFT layers, including the gate silicon nitride, the undoped, and the n+ amorphous silicon were deposited at a substrate temperature of 150°C. The transistors have inverted-staggered back-channel etch structure. The TFT off-current is ∼ 10−12 A, the on-off current ratio is > 107, the threshold voltage is 3.5 V, the sub-threshold slope is ∼ 0.5V/decade, and the linear-regime mobility is ∼ 0.5 cm2V−1s−1. We compare the mechanical behavior of a thin film on a stiff and on a compliant substrate. The thin film stress can be reduced to one half by changing from a stiff to a compliant substrate. A new equation is developed for the radius of curvature of thin films on compliant substrates.