# Exercise 3.4-1

## Quick Questions to

### 3.4 Structure, Interface and Some Properties

| Here are some quick questions:
|  | What is epitaxial growth? Consider the possibility of epitaxial growth; giving possible conditions (e.g. with respect to structures, lattice constants, ...) and use simple pictures: A on A. A (fcc) on B (fcc). A (fcc) on C (hex). A (fcc) on B (fcc) with intermediate layer. ....
|  | B (fcc; (100)) with lattice constant aA is deposited on A (fcc; (100) with aB = 0.95 aA. Sketch the structure for Thickness of B only a few atomic layers. Thickness of B > 50 nm
|  | Difficult! Sketch a pure edge misfit dislocation network on a {100} interface plane for a misfit of 10 % for the case of Burgers vector of the dislocations is b = a<100>. Burgers vector of the dislocations is b = a/2<110>.
|  | Difficult! What would happen if the (square) network of misfit dislocations on a {100} type interface would be changed from edge dislocations to screw dislocations?
|  | What are the energetic reasons for introducing misfit dislocations into epitaxial interface it the layer thickness is larger than a critical thickness? What determines the critical thickness?
|  | Sketch the curve for the critical thickness dcrit in a dcrit - misfit diagram, Try to give approximate numbers.
|  | Enumerate and discuss structures obtainable with thin films but not (easily) with bulk materials. Give examples for applications.
|  | Give reasons why thin film properties can be quite different from bulk properties; give examples.
|  | Name some technologically extremely important special thin film properties; discuss with actual numbers.

With frame

3.4.4 Summary to: 3.4 Structure, Interface and Some Properties

© H. Föll (Semiconductor Technology - Script)