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Unformatted text preview: Temperature
Carrier Concentration EE 332 Spring 2013 Operating Temperature of Semiconductor
Operating Temperature of Semiconductor EE 332 Spring 2013 Dependence of EF oon Temperature and Doping
Dependence of E n Temperature and Doping
F EE 332 Spring 2013 A Real Example An Example – MOS Transistor EE 332 Spring 2013 Compensation
Compensation Process Process
• Semiconductors can be doped with both donors and acceptors
simultaneously. • Assume a material doped with Nd>Na predominantly n-type so EF lies
above acceptor level Ea completely full, however, with EF above Ei, the hole
concentration cannot be equal to Na. • Mechanism:
– Electrons are donated to the conduction band from the donor level.
– An acceptor state gets filled by a valence band electron, thus creating a hole in
the valence band.
– An electron from the conduction band recombines with this hole.
– Extending this logic, it is expected that the resultant concentration of electrons in
the conduction band would be Nd-NA instead of Nd.
– This process is called compensation. • By compensation, an n-type material can be made intrinsic (by
making Nd=NA ) or even p-type (for NA>...
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- Spring '09