Module 6 2 Flashcards
What is the Punch Through Effect in MOS transistors?
Depletion region boundaries of source and drain meet to form a single depletion region.
This effect can lead to increased current flow and reduced control over the device.
Define Velocity Saturation in the context of MOS transistors.
Carrier velocity is linear and increases with electric field until saturation occurs, after which mobility decreases.
This phenomenon is critical in small geometry FETs.
What does DIBL stand for?
Drain-Induced Barrier Lowering.
This effect occurs when high velocity carriers near the drain gain extra energy, reducing the total current flow.
Describe the Hot Carrier Effect.
Carriers gain extra energy and can tunnel through gate oxide, altering current flow and reducing input impedance.
This effect can affect device reliability.
What impact does Mobility Degradation have on MOS transistors?
Reduction of drift velocity and mobility due to zig-zag paths caused by vertical electric fields from gate voltage.
This degradation significantly influences current-voltage characteristics.
Fill in the blank: The threshold voltage in MOS transistors can be influenced by the _______.
DIBL effect.
True or False: In small geometry FETs, the inversion is solely due to the fields of the gate.
False.
The inversion is influenced by both gate-to-source voltage and drain-to-source voltage.
What is the relationship between electric field strength and carrier velocity in MOS transistors?
Carrier velocity increases with electric field strength until it saturates.
Beyond saturation, the mobility of electrons decreases.
List the factors that cause Mobility Degradation.
- Vertical electric field from gate voltage
- Zig-zag path of carriers
These factors lead to a significant reduction in current flow.
What happens to the input impedance of a MOS transistor due to the DIBL effect?
It reduces the input impedance.
This alteration can affect the overall performance of the device.
What occurs to carriers in the presence of high velocity near the drain?
They gain extra energy, becoming hot carriers.
This energy gain can lead to tunneling through gate oxide.
