Forward Biasing a Diode: Explained

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In summary, the movement of majority carriers and holes in a forward-biased p-n junction creates a net flow of current. Additional holes from the p material move in to fill in the deficit created by electrons from the depletion region, while electrons from the wire contact keep moving into the depletion region. This process also occurs in the n material. It is unclear if joining an n-type material with intrinsic material and applying an external voltage would result in conduction without e-h pair generation.
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unseensoul
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There are a lot of resources out there which mention that when a diode is forward biased the majority carriers at the n-type material will move to the p-type material "through" the holes therefore the holes will move from the p-type region to the n-type region.

However, this doesn't make any sense to me at all...

As the majority carriers in the n-type region are at an excited state they are free to move about the material. Therefore when the diode is forward biased (assuming that external voltage is higher than barrier potential) the majority carriers (electrons) in the n-type region would move along the p-type material without recombining with the holes.
However, the holes would still move in opposite direction not due to the n-type's majority carriers but due to the neighbour valence electrons (which aren't in an excited state) being pushed due to the external voltage.

This explanation makes much more sense to me than the first one although I'm not sure whether that's what real happens.

I'd like to "hear" your suggestions/thoughts...

Edit:

http://img21.imageshack.us/img21/9639/84077772ht7.jpg" illustrates what I'm talking about; Notice the hole in the middle moving to the right plus the free electron at the top moving in opposite direction.
 
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Ok, I'll make the question in this way...

Would there be conduction if I joined a n-type material (extrinsic) with an intrinsic silicon material and connected an external voltage across both ends (neglecting e-h pair generation)?
 
  • #3
In a forward-biased p-n junction, electrons from the depletion region are pushed further into the p material where they quickly recombine with holes.

As I understand it, this creates a deficit of holes, the majority carrier, in the p material. Additional holes are available and abundant in the p material, and move into "fill in" the deficit. Additional holes keep moving in from the wire contact (actually, the wire keeps removing electrons to create additional holes in the p material.)

The net flow of holes in most of the p material, and the flow of electrons from the depletion region into a short distance of the p material, maintain the same net current throughout the material.

An analogous process occurs in the n material.

Hope that is clear enough. I have always struggled to understand this on a microscopic scale, and have pretty much resigned myself to accepting the v-i curve for what it is.

Would there be conduction if I joined a n-type material (extrinsic) with an intrinsic silicon material and connected an external voltage across both ends (neglecting e-h pair generation)?
Hmmm, don't know if this is done in practice. I know that sometimes a thin intrinsic-material layer is used between the p and n regions, I think to lower capacitance in for example p-i-n photodiodes.
 

1. What is forward biasing a diode?

Forward biasing a diode is the process of applying a positive voltage to the anode and a negative voltage to the cathode, allowing current to flow through the diode. This allows the diode to conduct electricity and function as a switch or rectifier in an electronic circuit.

2. How does forward biasing affect the behavior of a diode?

Forward biasing reduces the resistance of the diode, allowing current to flow through it. This causes the diode to turn on and allow current to pass through, and the voltage across the diode decreases. The diode will continue to function in this manner until the voltage across it becomes too high, at which point it will enter breakdown and potentially be damaged.

3. What are some applications of forward biasing a diode?

Forward biasing is commonly used in electronic circuits to rectify AC signals, meaning it allows the current to flow in one direction and blocks it in the other. This is useful for converting AC power to DC power, such as in power supplies. Diodes are also used in voltage regulators, signal demodulation, and in digital logic gates.

4. How is forward biasing different from reverse biasing?

In reverse biasing, the diode is connected with the positive voltage applied to the cathode and the negative voltage applied to the anode. This creates a high resistance barrier that prevents current from flowing through the diode. In contrast, forward biasing allows current to flow through the diode and reduces the resistance barrier.

5. What factors can affect the forward biasing of a diode?

The forward biasing of a diode can be affected by the voltage applied, the temperature of the diode, and the material properties of the diode. Different types of diodes, such as silicon and germanium, have different forward voltage thresholds and temperature coefficients. It is important to consider these factors when designing and using electronic circuits with diodes.

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