Impurity diffusion vs redistribution in semiconductors

In summary, the conversation discusses diffusion and dopant redistribution in semiconductors. The diffusion follows diffusion laws and the diffusion equation relates the rate of change of concentration with time and physical space. This means that diffusion will occur from areas of higher to lower concentration, similar to other familiar cases of diffusion.
  • #1
setareh
1
0
Hi,
Could any kine soul please explain this to me:

I know that diffusion is movement of impurities (dopants) into the semiconductor especially happening during heat cycles in fabrication process. but what is the dopant redistribution? Is it movement of impurities toward the surface?

Thanks in advance
 
Engineering news on Phys.org
  • #2
The diffusion follows diffusion laws.

The diffusion equation says:

The rate of change of concentration in time is equal to the rate of change in physical space of the the product of diffusion coefficient and the rate of change of the concentration in physical space.

If your diffusion concentration doesn't change with physical location this reduces to:

The rate of change of concentration in time is equal to the diffusion coefficient times the rate of change of the rate of change of the concentration in space.

What this means is that movement will be toward physical locations of higher concentration to less concentration - just like most familiar cases of diffusion are probably understood intuitively. Solid state diffusion is really no different from fluid diffusion in a liquid or a gas only far slower and/or more temperature dependent.
 

1. What is impurity diffusion in semiconductors?

Impurity diffusion in semiconductors is the process of introducing foreign atoms, or impurities, into a semiconductor crystal. This is typically done through processes such as ion implantation or diffusion from a gas source. The impurities alter the electrical and optical properties of the semiconductor, allowing for the creation of different types of electronic devices.

2. What is redistribution in semiconductors?

Redistribution in semiconductors is the movement of impurities within the semiconductor crystal after they have been introduced. This can occur through processes such as thermal diffusion, where the impurities are redistributed due to temperature changes in the crystal. This redistribution can affect the performance of electronic devices and must be carefully controlled.

3. What is the difference between impurity diffusion and redistribution in semiconductors?

The main difference between impurity diffusion and redistribution is the stage at which they occur in the semiconductor manufacturing process. Impurity diffusion is the initial introduction of impurities into the crystal, while redistribution is the subsequent movement of these impurities. Additionally, impurity diffusion is a deliberate process, while redistribution can occur naturally or be induced by external factors.

4. How do impurity diffusion and redistribution affect the performance of semiconductors?

Impurity diffusion and redistribution can significantly impact the electrical and optical properties of semiconductors. The introduction of impurities can create charge carriers and change the conductivity of the material, while redistribution can alter the concentration and distribution of these impurities. This can affect the efficiency and functionality of electronic devices made from the semiconductor.

5. What factors influence impurity diffusion and redistribution in semiconductors?

Several factors can influence impurity diffusion and redistribution in semiconductors, including temperature, crystal structure, impurity concentration, and the type of impurities introduced. The rate and extent of diffusion and redistribution can also vary depending on the manufacturing process and techniques used. Careful control and understanding of these factors are essential for producing high-quality semiconductors for electronic devices.

Similar threads

Diffusion current and carrier concentration equilibrium (unbiased)
    • Electrical Engineering
Replies
1
Views
892
Semiconductor -- Conduction and Valence bands
    • Electrical Engineering
Replies
1
Views
768
Simulating Metal-Semiconductor Junction using SILVACO TCAD
    • Electrical Engineering
Replies
1
Views
2K
What goes on in a semiconductor.
    • Atomic and Condensed Matter
Replies
22
Views
6K
Reverse Bias in P-N Junctions: Why Don't Electrons Diffuse Back?
    • Atomic and Condensed Matter
Replies
4
Views
4K
How do solar cells generate current from pn-junctions?
    • Materials and Chemical Engineering
Replies
4
Views
4K
Understanding Capacitor Behavior for Noise Filtering?
    • Electrical Engineering
Replies
15
Views
3K
Ln sigma vs 1/T curve for p-type semiconductor
    • Advanced Physics Homework Help
Replies
1
Views
4K
Just curious about many things like hydrostatics
    • Mechanical Engineering
Replies
28
Views
2K
I Similarities / diffs between diffusion & wave propagation
    • Other Physics Topics
Replies
3
Views
3K

Hot Threads

Recent Insights

Back
Top