| Author | Message | ||
     Anonymous |
Mr. Simon I would appreciate if oyu could tell me how to make a solar cells out of silicon. | ||
| vocasla Unregistered guest |
out of silicon?! the only way I know how to make solar panels out of silicon is the following (although i am not too sure myself): Since silicon itself is unconductive, it is doped(adding impurities) in other chemicals to make it semi-conductive. There are two types of semiconductors, that is N-type and P-type. N-types have extra electrons that are free to move around. P-types have a lack of electrons that will accept extra electrons to fill its outershell. The element needed to make N-type semiconductor silicon is phospherous or arsenic. You can get phospherous from the inside of tube lightings like in the ones at school halls or my kitchen ceiling. For P-type semiconductor silicon you neeed boron or gallium. I don't know where to get these. Unfortunately you need high temperatures to melt them in order to mix the chemicals together. i think the reason why they choose silicon (i don't honestly know for sure) is probably because of its ability to absorb and convert a large percentage of frequencies of photons from sunlight into electrons (known as photoelectric effect) after it is doped with these materials. strangely, i was given a silicon crystal that costed my friend 2 pence (4 cents) the size of a shark tooth. | ||
| lysdexia Unregistered guest |
phosphorus All substances are conductive. Silicon is already a semiconductor; look where it damn is on the periodic table. Impurities are added to fine-tune the voltage to make it a conductor. Silicon can be crystallized to many many nines, and it's everywhere. | ||
| vocasla Unregistered guest |
i guess you are right lysexia, i just read this stuff from www.howstuffworks.com | ||
| vocasla Unregistered guest |
lysdexia, very sorry  | ||
| Daniel Garcia (Buckminsterfullerene) New member Username: Buckminsterfullerene Post Number: 1 Registered: 10-2005 |
There are 3 layers to a Solar Cell, first there is the Positive layer which is the one where the photons of light at a frequency of about 1.08 eV or greater strike the surface, this layer is doped with phosphorous as you said. The electrons that get nocked from orbit are sent to the Negative layer which as you said can be doped with Arsenic or Boron, though for environmental safety it is usually done with Boron. There is a layer in the middle which is the Intrinsic layer, this is where you get the flow of electrons, and potentially the main reason why the solar cell would produce electricity. The Intrinsic layer is composed of silicon and hydrogen. the process of purifying Silicon from SiO is one which actually requires most of the energy of making a solar cell: SiO + C + 2000 degrees Celcious ---> Si + CO2 you are basically burning silicon oxide in the presence of carbon in order to get carbon dioxide and pure silicon, note that in order for a solar panel to work you need the Silicon to be purified to about 99.9999%. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 762 Registered: 12-2004 |
Well, not quite. There are technologies that can make silicon solar cells from low purity silicon. And silicon solar cells are not PIN diodes, they are simply PN diodes. And electron-hole pairs are not only formed in the P region. In fact, they are formed everywhere, but are only useful when they form very close to the PN junction. And the phosphorus doped silicon is the N type, not the P type. A good introduction is here. And to Vocasla: The stuff inside a fluorescent light are phosphors, not phosphorus. You can get phosphorus from matches or extract it from bones, or just buy the pure stuff from a chemical supply store. |
