The width of the space charge region at a p-n junction is reduced by applying a voltage bias over the p-n junction. What is the correct statement on both the bias voltage and the p-n junction?
a)The voltage is a forward bias and the diffusion of the majority charge carriers becomes more dominant.
b)The voltage is a reverse bias and the diffusion of the majority charge carriers becomes more dominant.
c)The voltage is a forward bias and the drift of the minority charge carriers becomes more dominant.
d)The voltage is a reverse bias and the drift of the minority charge carriers becomes more dominant.
The answer is A
A
d) The voltage is a reverse bias and the drift of the minority charge carriers becomes more dominant.
To determine the correct statement, it's important to understand the concept of the space charge region, also known as the depletion region, at a p-n junction.
In a p-n junction, the space charge region is a region devoid of free charge carriers. It is created due to the diffusion of majority charge carriers, which leads to a build-up of immobile ions and creates an electric field that opposes further diffusion.
Now, let's analyze the statements:
a) The voltage is a forward bias and the diffusion of the majority charge carriers becomes more dominant.
b) The voltage is a reverse bias and the diffusion of the majority charge carriers becomes more dominant.
c) The voltage is a forward bias and the drift of the minority charge carriers becomes more dominant.
d) The voltage is a reverse bias and the drift of the minority charge carriers becomes more dominant.
To reduce the width of the space charge region, we need to induce a more dominant effect that counters the electric field in this region. This would involve increasing the movement of minority charge carriers or reducing the movement of majority charge carriers.
When a p-n junction is forward-biased, the positive terminal of the voltage source is connected to the p-side of the junction, and the negative terminal is connected to the n-side. This increases the flow of majority charge carriers across the junction.
On the other hand, when a p-n junction is reverse-biased, the positive terminal of the voltage source is connected to the n-side of the junction, and the negative terminal is connected to the p-side. This restricts the flow of majority charge carriers across the junction.
Since the diffusion of majority charge carriers builds up the space charge region, applying a reverse bias would push more majority carriers away from the junction, resulting in a wider space charge region. Conversely, applying a forward bias would increase the flow of majority charge carriers across the junction, reducing the width of the space charge region.
Therefore, the correct statement is:
a) The voltage is a forward bias and the diffusion of the majority charge carriers becomes more dominant.