What is punch through effect in a transistor?

[′pənch‚thrü] (electronics) An emitter-to-collector breakdown which can occur in a junction transistor with very narrow base region at sufficiently high collector voltage when the space-charge layer extends completely across the base region.

What is punch through condition?

Punch through is addressed to MOSFETs’ channel length modulation and occurs when the depletion regions of the drain-body and source-body junctions meet and form a single depletion region. In this case, the drain and source depletion regions will be reduced and no parasitic current path is formed.

What is punch through in VLSI?

The punch through mechanism is described as reverse bias applied to drain, which results into extended depletion region. My question (by looking at the attached figure) is that how intersection of two depletion regions with electric fields in opposite directions (Eleft and Eright) can results in “one” depletion region.

What is the principle of bipolar junction transistor action?

Bipolar transistors conduct current using both electrons and holes in the same device. Operation of a bipolar transistor as a current amplifier requires that the collector-base junction be reverse biased and the emitter-base junction be forward biased.

What is punch through and reach?

As the designed geometry thickness of the lightly doped side is less than the corresponding depletion width, punch-though phenomenon comes up. The reach-through effect appears when the designed geometry thickness of the heavily doped side is less than the corresponding depletion width.

Which of the following is the concept of drain punch through?

When the drain is at a high enough voltage w.r.t. source,the depletion region around the drain may extend to source,thus causing a current to flow irrespective of the gate voltage. This is Punchthrough condition.

What is hot electron effect?

The hot electron (or short channel) effect is described in as occurring when a high voltage is applied across the source and drain of a device, the electric field is high, and the electrons are accelerated in the channel.

What are the four main parts of the JFET?

There are basically 4 regions of operation for JFET.

Ohmic Region: In this region the JFET will act as a voltage controlled resistor.
Cut off Region: JFET will act in the cut off state when Vgs is sufficient to cause the JFET to act as an open circuit.
Active Region: This region is also called as the saturation region.

What is punch through effect of NMOS transistor?

That’s the punch-through effect. And, the concept is simple. It’s just that, when you bias your NMOS transistor, with Vd as increasing +ve voltage, Vs grounded, the drain-substrate goes reverse bias, and hence a depletion region starts to get formed near drain region at lower voltages of Vd, as shown below: This is tricky.

What does punch through mean in a transistor?

This is the punch through current signifying the onset of punch through breakdown. Yes your expectation is correct, VDS lower the source potential barrier meaning decreasing g the built in electric field by imposing an applied opposite electric field. Thank you Dr. Zekry, I appreciate your helpful answer.

How does punch through mechanism work in MOSFET?

The punch through mechanism is described as reverse bias applied to drain, which results into extended depletion region. The two depletion regions of drain and source therefore are intersectioned with each other, and this results into “one” depletion region, and flow of leakage current and consequently breakdown of MOSFET.

How to avoid the undesired punch-through effect?