Metal Semiconductor contact (Part 2)

[Robotduck]

TL;DR Summary

Metal Semiconductor contact

MOS (p type)

1) Figure a) and b) are the cases of strong inversion. Figure b)-For high frequency signals, electrons at the semiconductor oxide interface do not get enough time to change ( I follow that ), but how come the charge in the bulk close to the depletion region changes with these high frequency signals and causes the change in the depletion region in the bulk ( which is bothering me )?
2)In Figure c) if we change the voltage ( ranging from accumulation to strong inversion )quickly, then the system does not have enough time for strong inversion but again - how come the charge in the bulk is responding with this change ?
3) How come the charge in the Metal is responding to these changes in figure b) and c) ? This also has the electrons as a majority carriers ?

Thank you in advance for taking time to answer these questions !

 

[azntoon]

1) In Figure b), the high frequency signals cause the electrons at the semiconductor oxide interface to move quickly between the oxide and the bulk semiconductor. This movement of electrons causes a redistribution of charge in the bulk, leading to a change in the depletion region. 2) In Figure c), when the voltage changes quickly from accumulation to strong inversion, the electrons in the bulk are not able to move quickly enough to reach the inversion layer. The charge that is already present in the bulk does not have time to be redistributed, and so the depletion region in the bulk remains unchanged. 3) The metal is responding to these changes because it is in contact with the semiconductor, and the electrons in the metal can be attracted to the semiconductor when the voltage changes. This causes a redistribution of charge in the metal, leading to a change in the potential of the metal.