p.2
Barrier Formation and Depletion Region
What occurs after a few recombinations around the junction in a PN junction?
A restraining force, known as the Barrier, is set up.
p.5
Reverse Bias Operation
What is the condition for a PN junction to be considered reverse biased?
The positive terminal of the battery is connected to the N-side and the negative terminal to the P-side.
p.3
Barrier Formation and Depletion Region
What prevents electrons from diffusing into the P-region?
The uncompensated -ve charge of immobile carriers in the P-region.
What are the three possibilities when voltage is applied across a semiconductor diode?
No Bias (V=0), Forward Bias (V>0), Reverse Bias (V<0).
p.6
Symbol and Terminology of PN Junction Diode
What do the P-region and N-region of a diode represent?
The P-region is called the Anode and the N-region is called the Cathode.
p.5
Reverse Bias Operation
What happens to holes and electrons in a reverse-biased PN junction?
Holes in the P-region are attracted to the negative terminal, and electrons in the N-region are attracted to the positive terminal.
p.1
P-type and N-type Semiconductors
What are P-type and N-type semiconductor materials used for?
They are used separately but have very limited use.
p.6
Current Flow in Diodes
What is the current due to minority carriers called?
Reverse Saturation Current.
p.4
Forward Bias Operation
What happens in the p-type material during forward bias?
An electron breaks a bond and enters the positive terminal, creating a hole that drifts towards the junction.
p.4
Forward Bias Operation
In which direction does conventional current flow in a forward-biased PN-junction?
From the p-side to the n-side.
p.6
Current Flow in Diodes
How does the Reverse Saturation Current behave with changes in battery voltage?
It remains the same whether the battery voltage is increased or decreased.
p.6
Symbol and Terminology of PN Junction Diode
In which direction does the arrow in the PN junction diode symbol point?
From the P-region to the N-region, indicating conventional current flow.
p.2
Barrier Formation and Depletion Region
What remains uncompensated when holes and free electrons recombine in a PN junction?
Negative acceptor ions in the P-region and positive donor ions in the N-region.
p.4
Forward Bias Operation
What occurs due to the negative potential applied to the N-side in forward bias?
Electrons are repelled from the negative terminal and move towards the junction.
p.5
P-type and N-type Semiconductors
What factors influence the generation of minority carriers?
Temperature, due to the breaking of covalent bonds with temperature rise.
What causes the diffusion of holes and electrons in a PN junction?
Thermal energy and different concentration levels in the two regions.
p.2
Barrier Formation and Depletion Region
What is the restraining force that stops further diffusion of holes and electrons in a PN junction?
The Barrier or Potential Barrier.
p.4
Forward Bias Operation
What is the effect of the positive potential applied to the P-side in forward bias?
Holes are repelled from the positive terminal and move towards the junction.
p.4
Forward Bias Operation
What type of current flows through the external circuit in forward bias?
Electron current flows through the external circuit.
p.5
Barrier Formation and Depletion Region
What effect does reverse bias have on the depletion region?
It widens the depletion region and increases the barrier potential.
p.5
Barrier Formation and Depletion Region
How does the increased barrier potential affect majority carriers?
It makes it more difficult for majority carriers to diffuse across the junction.
p.5
Current Flow in Diodes
What happens to minority carriers as soon as they are generated?
They are swept across the junction, allowing a very small current to flow.
p.3
Potential Barrier in Semiconductors
What is the width of the barrier?
The physical distance from one side of the barrier to the other.
What happens to holes from the P-region when the PN junction is formed?
They diffuse into the N-region and combine with free electrons.
What happens in the case of no applied bias (V=0V)?
The diode is in a neutral state with no current flow.
p.4
Forward Bias Operation
What occurs during the recombination of electrons and holes in forward bias?
An electron from the negative terminal enters the n-type material and drifts towards the junction.
p.5
Reverse Bias Operation
What assists minority carriers in crossing the junction in a reverse-biased diode?
The increased barrier potential.
p.6
Current Flow in Diodes
Why is the Reverse Saturation Current very small?
Because the number of minority carriers is small.
p.3
Potential Barrier in Semiconductors
What is the height of the barrier?
The difference of potential from one side of the barrier to the other.
p.1
Semiconductor Diode Characteristics
What is a semiconductor diode?
A useful device formed by a PN-junction.
p.4
Forward Bias Operation
What happens to the depletion region when the PN-junction is forward biased?
The potential barrier reduces, and the width and height of the depletion region decrease.
p.5
Forward Bias Operation
What occurs to majority carriers when the PN junction is forward biased?
More majority carriers diffuse across the junction, increasing current.
p.3
Barrier Formation and Depletion Region
What role does the Barrier play for minority carriers?
It helps them to drift across the junction.
p.4
Forward Bias Operation
What happens when a battery is connected to a PN-junction with the positive terminal to the P-side?
The PN-junction is said to be Forward Biased.
p.5
Reverse Bias Operation
What happens to the barrier potential when battery voltage is increased?
The barrier potential is further reduced.
p.3
Barrier Formation and Depletion Region
What prevents holes from diffusing into the N-region?
The uncompensated +ve charge in the N-region.
p.6
Symbol and Terminology of PN Junction Diode
What is the symbol for a PN junction diode?
It resembles an arrow pointing from the P-region (Anode) to the N-region (Cathode).
p.3
Current Flow in Diodes
Can majority carriers overcome the barrier?
Yes, but this does not mean that current flows since there is no circuit connected.
