Chapter 1 - (lec 2)

Question 1

Crystalline Solid

Answer 1

A basic 3d atomic pattern is repeated all over the material

Question 2

Amorphous Solid

Answer 2

No pattern- atoms are placed at random

Question 3

Polycrystalline solid

Answer 3

Many small regions of single-crystal patterns separated by void spaces

Question 4

Explain a crystal Lattice and the components that make it up

Answer 4

Lattice - basic 3d grid pattern that is repeated over the material
Unit cell- Repeating 3d atomic pattern is called a lattice
Lattace constants - side lengths of the lattice ABC

Question 5

Describe the 3 basic type of uni cell from the slides and name them give an example of an element for each

Answer 5

Simple cubic (polonium) - Equal side lengths no extra atoms
Body centered cubic (iron chromium) - Cubic lattice with an extra atom in the centre of the cube
Face centered cubic (copper gold)- cubic with two sets of 3 extra atoms arranged in two triangles on each face

Question 6

Give a few eamples of Elemental Semiconductors with a Diamond Structure

Answer 6

Si, Ge, C all group IV

Question 7

Describe the Diamond structure in terms of a basic lattice type

Answer 7

Can be through of as an Face Centred Cubic (FCC) lattice with an extra atom placed at a/4 + b/4 + c/4 from each of the FCC atoms

Question 8

What is a Zinc Blende in terms of a diamond structure

Answer 8

Many compounds such as GaAs or InP atoms are arranged in a basic diamond structure but the extra atoms in each unit cell come from the other element in the compound

Question 9

What is a covalent bond

Answer 9

Electrons that are shared by two neighboring atoms

Question 10

What is a Tetrahedra bond

Answer 10

Every atom is bonded to its four nearest atoms through 4 covalent bonds tetra is 4 hence the 4 bonds

Question 11

How are atoms bonded in a Sillicone lattice

Answer 11

Tetreahedraley bonded

Question 12

Explain what a Miller Indices is and the variables associated with it

Answer 12

A plane identified by three integers h k and I
h- the interceprt of the plane along the x axis in units of lattice constant
k- intercept of the plane along the y axis in lattice constant units
I - intercept of the plane along the Z axis

HKI = XYZ - same order for memorization

Question 13

Explain crystal directions

Answer 13

The direction of a vector normal to a plane
represented by 3 integers in square brackets [hkl] no spaces or commas

Question 14

Name all (4) miller indices and their notations

Answer 14

(hkl) -Crystial plane - round brackets
{hkl} - Equicvalent plane - curly brackets
[hkl] - crystal direction - Square brackets

<hkl> Equivalient direction - Arrows
</hkl>