### 3.4.4 Summary to: 3.4 Structure, Interface and Some Properties

| Epitaxial layers are crucial for semiconductor technology. |  |
|  | Misfit of lattice constants will produce strained layers upon epitaxial growth; strain relief happens by the formation of misfit dislocations. |
|  | Misfit dislocatipons must be avoided at all costs! |
|  | Below a usually rather small critical thickness dcrit of the the thin layer no misfit dislocations will occur. |
|  | Rule of thumb: 0.5 % misfit Þ dcrit »10 nm |  |
| The internal structure of thin films can be anything known from bulk materials plus some (important!) specialities. |  |
a-Si: Micro electronics a-Si:H: Solar cells, LCD displays µc-Si:H: Solar cells
| Properties of thin films can be quite different from that of the bulk material |  |
Much better in thin films Electrical break-down field strength of dielectrics. Critical current densities in conductors.
|  | The reason can be differences in length scales. |
|  | Semiconductor technology relies to some extent on superior thin film properties |
Exercise 3.4-1
All Questions to 3.4

© H. Föll (Semiconductor Technology - Script)