Depletion zone of a n-i junction

In summary, the conversation discusses the calculation of the depletion zone in a junction between n doped and intrinsic GaAs. It is mentioned that in a p-n junction, the depletion zone is calculated under the condition of electro-neutrality. The possibility of the depletion zone being mostly in the i-GaAs in a p-i-n structure is also considered, along with the width of the depletion zone in photodiodes and RF switch devices. The speaker also brings up the idea of the i region being a feebly doped p region, resulting in a depletion layer entering over the i-GaAs.
  • #1
IRobot
87
0
Hi,
I am interested in a junction between n doped and intrinsic GaAs, specifically the localization and width of the depletion zone (where the built-in E field is). In a p-n junction the depletion zone is calculated under the condition of electro-neutrality, if I see i-GaAs as really really low doped p-GaAs, can I consider that the depletion zone will be mostly in the i-GaAs? (I have in mind a juxtaposition of one layer of n-GaAs with a layer of i-GaAs which has twice the width of the first one)
 
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  • #2
In a p-i-n structure, the depletion zone looks similar to that of a p-n but with the additional i region in the center. In photodiodes and RF switch devices, the i region width d is (I think) much larger than the widths of the depletion zones in the p and n layers, so the total depletion width will be a little larger than d.
 
  • #3
Well, in my case there is no p-layer behind the i region, the piece is really engineered like that. Or at least it is presented like that in the article based on this device.
At the moment, I am really inclined to look at the i region as a p region feebly doped in comparison to the n one, and in this case I would have a depletion layer entering over the i-GaAs.
 

What is the depletion zone of a n-i junction?

The depletion zone, also known as the depletion region or space charge region, is a thin layer of depleted charge carriers that forms at the interface of a n-type and intrinsic (i) semiconductor in a n-i junction. It is created due to the diffusion of electrons and holes across the junction, resulting in a built-in electric field that prevents further diffusion.

How does the depletion zone affect the behavior of a n-i junction?

The depletion zone plays a crucial role in the functioning of a n-i junction. It acts as a barrier to the flow of current, making the junction behave like a diode. It also creates a potential difference across the junction, known as the built-in potential, which is essential for various electronic devices such as solar cells and transistors.

What factors affect the size of the depletion zone?

The size of the depletion zone is primarily determined by the doping levels of the n and i regions, as well as the applied voltage across the junction. Higher doping levels result in a thinner depletion zone, while a reverse bias voltage will widen the depletion zone. Additionally, temperature can also affect the size of the depletion zone.

Can the depletion zone be manipulated?

Yes, the depletion zone can be manipulated by applying an external voltage to the n-i junction. A forward bias voltage will decrease the size of the depletion zone, allowing current to flow through the junction. On the other hand, a reverse bias voltage will increase the depletion zone's size, reducing the current flow.

What is the significance of the depletion zone in solar cells?

In a solar cell, the depletion zone plays a crucial role in converting light energy into electrical energy. When photons from sunlight strike the depletion zone, they create electron-hole pairs, which are then separated by the built-in electric field and collected as current. This process is the basis of how solar cells generate electricity.

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