### 2.2.2 Other Uses of Silicon

The Obvious

| As a budding Materials Scientist and Engineer, you must have heard or read about at least two other major Si products. If not, do the following: i) Start reading a real newspaper and ii) Read the Science and Technology part. What you definitely should be able to come up with are. |  |
Solar Cell
| Solar Cells. |
|  | What do you know about solar cells? Quite a bit, actually - provided you remembered what you have learned already. |
|  | Let's recapitulate a few essentials you should know: |
|  | Maximum efficiency h and how it relates to the band gap. The energy density given by the sun and how much power we can generate at high noon per m2. The fact that we need a (pn-) junction to collect minority carriers. The fact that the diffusion length L plays a major role, and that this has to do with Si being an indirect semiconductor The I-U characteristics and how it is calculated. That the only decisive parameter in the solar cell business is money. |
| "MEMS", i.e. microelectronic and micro-mechanic (and micro-optics and micro-fluidic and...) systems. |  |
MEMS device Courtesy of Sandia National Laboratories, SUMMiTTM Technologies, "www.mems.sandia.gov"
|  | What do you know about MEMS? Probably not all that much from what you have learned so far. |
|  | Class Exercise: What do you know about MEMS? |
|  | To get some idea of what is going on in your immediate neighborhood in Itzehoe, check this link! |
| We will come to these devices or components in due course. Meanwhile you can activate the link and look ahead a bit. |
| Now ask yourself: Class Exercise: Are there any other uses of Si you know off (or can find quickly)? |
|  | Only after you pondered the questions above for some time, you should activate this link |

© H. Föll (Semiconductor Technology - Script)