Semiconductor Basics: Drift & Diffusion Current

In summary, the conversation is about the concepts of drift and diffusion current in a semiconductor diode. When there is no bias, diffusion causes the transfer of charges and creates a depletion region, which then produces an electric field leading to drift current. In forward bias, there is a potential difference and an electric field, so the current is due to the battery voltage. The question is whether there is still diffusion after the battery is applied, and some argue that drift current only depends on temperature. The person is confused about the concept of drift current and is seeking help.
  • #1
timkuc
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My question is about drift and diffusion current.In a semiconductor diode no "bias" condition diffusion is present and due to transfer of charges due to diffusion depletion region created and then this region has ions which produce electric field which results in drift current due to force the minority charges from both the sides.So the diffusion current and after that drift current comes into picture .In forward bias there will be potential difference across the diode so there must be electric field in the diode.So in forward bias current should be due to the battery voltage .What I don't understand is ,is there any phenomenon of diffusion after applying the battery (because battery produces electric field in material,that means only drift current should be there as the drift current definition says "Drift current is the movement of electrons in electric field) ? Some says that drift current only depends on temperature (Why ?). I think don't getting the drift current what it really is . I am in really in trouble.
 
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FAQ: Semiconductor Basics: Drift & Diffusion Current

1. What is drift current in semiconductors?

Drift current in semiconductors is the movement of charge carriers (electrons or holes) due to an applied electric field. This type of current is responsible for the flow of charges in a semiconductor device such as a transistor.

2. How does diffusion current differ from drift current?

Diffusion current is the movement of charge carriers due to a concentration gradient, rather than an electric field. It is caused by the random motion of charge carriers and is present even in the absence of an electric field. In contrast, drift current is only present when an electric field is applied.

3. What is the relationship between drift and diffusion current?

Drift and diffusion current are both components of the total current in a semiconductor device. They work together to maintain equilibrium and establish a steady-state current flow. In most cases, drift current dominates over diffusion current.

4. How does temperature affect drift and diffusion current?

As temperature increases, the random motion of charge carriers increases, resulting in an increase in diffusion current. However, the mobility of charge carriers also decreases with increasing temperature, causing a decrease in drift current. Overall, an increase in temperature can lead to an increase or decrease in the total current, depending on the specific semiconductor material and conditions.

5. Can drift and diffusion current be controlled in semiconductor devices?

Yes, drift and diffusion current can be controlled through the use of doping, which involves intentionally introducing impurities into the semiconductor material. Doping can alter the number and type of charge carriers, thereby affecting the overall current flow in a semiconductor device.

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