08-08-2012, 02:26 PM
Review of Semiconductor Physics, PN Junction Diodes and Resistors
3semicond_diode.ppt (Size: 628 KB / Downloads: 62)
What Is a Semiconductor
Many materials, such as most metals, allow electrical current to flow through them
These are known as conductors
Materials that do not allow electrical current to flow through them are called insulators
Pure silicon, the base material of most transistors, is considered a semiconductor because its conductivity can be modulated by the introduction of impurities
Crystalline Solids
In a crystalline solid, the periodic arrangement of atoms is repeated over the entire crystal
Silicon crystal has a diamond lattice
What’s so special about Silicon?
Cheap and abundant
Amazing mechanical, chemical and electronic properties
The material is very well-known to mankind
SiO2: sand, glass
Semiconductor Crystalline Structure
Semiconductors have a regular crystalline structure
for monocrystal, extends through entire structure
for polycrystal, structure is interrupted at irregular boundaries
Monocrystal has uniform 3-dimensional structure
Atoms occupy fixed positions relative to one another, butare in constant vibration about equilibrium