Fabrication of the semiconductor devicesUnit cell of siliconcrystal is cubicEach Si atom has 4nearestneighbours5.43A
Fabrication of the semiconductor devices • Unit cell of silicon crystal is cubic. • Each Si atom has 4 nearest neighbours
EcTop ofconduction bandEg=9eVemptyEcE.=1.1 eVfilledEvEvEcConductorSio, (Insulator)Si (Semiconductor)
Conduction bandEBand gapEEValence band Energy band diagram shows the bottom edge of conduction bandEc, and top edge of valence band, E, : E。 and E, are separated by the band gap energy, Eg
Dopants in SiliconSi: Si:SiSiSiSiB: Si:Si: As: Si:SiSi: Si: Si:Si: Si: Si: As, a Group V element, introduces conduction electrons and createsN-type silicon, and is called a donor.? B, a Group III element, introduces holes and creates P-type silicon.and is called an acceptor
Measuring the Band Gap Energy by Light AbsorptionelectronEcphotonsEgphoton energy: hv> EgEvOhole: E. can be determined from the minimum energy (hv) ofphotons that are absorbed by the semiconductor.Bandgap energies of selected semiconductorsSemi-DiamonsiGeGaPdInSbGaAsZnSeconductor62.70.180.671.121.422.25Eg (eV)