Electrical Properties (Concepts) Flashcards
responses to applied electric field
electrical properties
movement of electrically charged particles through a transmission medium
conduction
two types of conduction
electronic and ionic
the energy corresponding to the highest filled state at 0K
Fermi energy, Ef
2 factors affecting conductivity
- number of free electrons
- electron mobility - affected by the presence of scattering centers: temperature, plastic deformation, impurities
two types of semiconductors
- intrinsic
- natural semiconductor
- # electrons = # holes - extrinsic
- enhanced by impurities
- # electrons ≠ # holes
when an electron is excited onto the conduction band, a vacant energy state is left in the valence band
hole
the addition of another element to make it easier for charge carriers to flow
doping
occurs when impurities are added with a different # valence e- than the host
Extrinsic Conduction
- type of extrinsic semiconductors where we add elements containing MISSING ELECTRONS (Group III in the periodic table)
- in the electronic band structure, it is the acceptor
P-type
type of extrinsic semiconductors where we add elements containing EXTRA ELECTRONS (Group V in the periodic table)
- in the electronic band structure, it is the donor
N-type
higher energy states not accessible due to gap (> 2 eV).
insulators
Ionic conduction is aided by the presence of this defect called ___________.
Schottky defect
The more ________________ the ions, the better the conduction.
charged
- Describes the ability of insulators to store a charge when under an electric field
- Measured by capacitance
Dielectric Behavior
- are dipolar below Curie TC = 120ºC
- cooled below Tc in strong electric field - make material with strong dipole moment
Ferroelectric Ceramics
application of pressure produces current
Piezoelectricity
For metals, conductivity is increased by:
– reducing deformation
– reducing imperfections
– decreasing temperature
For pure semiconductors, conductivity is increased by:
– increasing temperature
– doping
A dielectric is an electrical (1)__________ that can be (2)___________ by an applied electric field.
(1) insulator
(2) polarized
