Silicon is a four-fold coordinated atom that is normally tetrahedrally bonded to four neighboring silicon atoms. In crystalline silicon this tetrahedral structure is continued over a large range, forming a well-ordered lattice (crystal).

In amorphous silicon this long range order is not present and the atoms form a continuous random network. Not all the atoms within amorphous silicon are four-fold coordinated. Due to the disordered nature of the material some atoms have a dangling bond. These dangling bonds are defects in the continuous random network, which cause anomalous electrical behavior.

If desired, the material can be passivated by hydrogen, which bonds to the dangling bonds and can reduce the dangling bond density by several orders of magnitude. Hydrogenated amorphous silicon (a-Si:H) has a sufficiently low amount of defects to be used within devices. However, the hydrogen is unfortunately associated with light induced degradation of the material, termed the Staebler-Wronski Effect.

[edit] Amorphous silicon and carbon
Amorphous alloys of silicon and carbon (amorphous silicon carbide, also hydrogenated, a-Si1-xCx:H) are an interesting variant to this material. Introduction of carbon adds extra freedom to controlling the properties of the material. The film could also be made transparent to visible light.

Increasing concentrations of carbon in the alloy widen the electronic gap between conduction and valence bands (also called “optical gap” and bandgap), in order to potentially increase the light efficiency of solar cells made with amorphous silicon carbide layers. On the other hand, the electronic properties as a semiconductor (mainly electron mobility), are badly affected by the increasing content of carbon in the alloy, due to the increased disorder in the atomic network.

Several studies are found in the scientific literature, mainly investigating the effects of deposition parameters on electronic quality, but practical applications of amorphous silicon carbide in commercial devices are still lacking.

[edit] Applications
While a-Si suffers from lower electronic performance compared to c-Si, it is much more flexible in its applications. It may also produce savings on silicon material cost, as a-Si layers can be made thinner than c-Si.

One advantage is that a-Si can be deposited at very low temperatures, as low as 75 degrees Celsius. This allows for deposition on not only glass, but plastic as well, making it a candidate for a roll-to-roll processing technique. Once deposited, a-Si can be doped in a fashion similar to c-Si, to form p-type or n-type layers and ultimately to form electronic devices.

Another advantage is that a-Si can be deposited over large areas by PECVD.

Amorphous silicon has become the material of choice for the active layer in thin-film transistors (TFTs), which are most widely used in large-area electronics applications, mainly for liquid-crystal displays (LCDs).

I stick to my research and digging……have read the Chinese websites and APWR will be making large noise very soon………..

??Our main acquisition objects in EVATECH are its two R & D centers and the amorphous silicon solar thin film equipment production line. After the acquisition, the two R & D centers will still remain in Japan focusing on the relevant R & D work, but amorphous silicon solar thin film and TCO glass coating production will be moved to China.
Furthermore, we have reached a common understanding with Shenyang Yuanda Enterprise Group that Yuanda will apply solar thin film to their main products curtain glass wall upon the realization of its production to be made in China. By union of Yuanda and Evatech’s strong technology, the competitiveness of our products will be enhanced through this strong-with-strong union.

Once you figure out Yuanda has built most of the Olympic venues in China and other monstrosity buildings all over the world (Frankfurt Rail Center), one see why APWR is about to soar!

Google Yuanda and then tell me this is going nowhere! We on a MOON ROCKET SOON riding APWR north!

Will APWR complete the aquisition of Eva_Tech from Japn out of bankruptcy and will APWR dive into solar panel production??? Will Eva_Tech add to APWR’s growth strategy in China by adding windows that are also solar panels?? The Chinese government is rumored to be also involved in this aquisition and I beleive this aquisition will solidify the involvement of the Chinese government into APWR for the long run using Shenyang Power Alliance as the key ingredient in green growth for China.