## 9.3 Epitaxial Layers

### 9.3.1 General Remarks

| Epitaxial layers play a very big role in compound semiconductor technology, while in Si it was only used for the bipolar technology. MOS and CMOS technologies for many generations could do with the (for Si expensive) epitaxial layer deposition techniques. In compound technology it is different for several reasons:
|  | The substrates are far less perfect than Si single crystals, and epitaxial layers usually have a better crystal quality than the substrates (this was also a main driving force behind Si epitaxy in the early days of Si technologiy in the seventies).
|  | There are more (and sometimes relatively cheap) methods to grow epitaxial layers of compound semiconductors.

© H. Föll (Semiconductors - Script)