Semiconductors
Semiconductors have mediumconductivity
Resistance depends
onthegeometryofthemetal
R R resistance
ftp
f resistivity
L length
A crosssectionalarea
BandStructure
Discrete Energy Levels
Electrons are notallowed to havethe sameenergy whentheirclouds havethesameposition
As we bring atoms closer electronclouds start to overlap
Whentwoatoms become close together energylevels willsplitinto two discretelevels
n b
Theequilibrium atomic spacing Theaverage distance betweentwoatomsthatare bonded
Electronslike to be in the lowestenergystate
Lowestenergy state is filled withelectronsfirstfollowedbyhigherenergylevels
ValanceBond The higheststatethatcontains
anyelectrons
Thenextstatewithhigherenergy will not haveanyelectrons
ConductionBand
Conductors no bandgapin betweenthevalenceandconductionbands
Even withverysmallamountofenergy electrons canjump to the empty conductionband
Insulators large bandgap between thevalence and conduction bands
Electrons need a verylargeamountofenergy to moveto conductionband
The band
gap ofa semi
conductor istypicallybetween 1 2eV
Semiconductors have mediumconductivity
Resistance depends
onthegeometryofthemetal
R R resistance
ftp
f resistivity
L length
A crosssectionalarea
BandStructure
Discrete Energy Levels
Electrons are notallowed to havethe sameenergy whentheirclouds havethesameposition
As we bring atoms closer electronclouds start to overlap
Whentwoatoms become close together energylevels willsplitinto two discretelevels
n b
Theequilibrium atomic spacing Theaverage distance betweentwoatomsthatare bonded
Electronslike to be in the lowestenergystate
Lowestenergy state is filled withelectronsfirstfollowedbyhigherenergylevels
ValanceBond The higheststatethatcontains
anyelectrons
Thenextstatewithhigherenergy will not haveanyelectrons
ConductionBand
Conductors no bandgapin betweenthevalenceandconductionbands
Even withverysmallamountofenergy electrons canjump to the empty conductionband
Insulators large bandgap between thevalence and conduction bands
Electrons need a verylargeamountofenergy to moveto conductionband
The band
gap ofa semi
conductor istypicallybetween 1 2eV
