How do I calculate misfit strain ?

  • Thread starter msPhysics
  • Start date
  • Tags
    Strain
In summary, the conversation is about calculating the misfit strain on InP and InGaAs when InGaAs is grown on InP. The lattice constants for InP and InGaAs are given as a1= 5.8687 and a2=5.7455 (with 25% In). The lattice mismatch ratio is calculated as -1.94%, indicating that InGaAs is under tension and InP is under compression. The concept of misfit strain is discussed, with the conclusion that the misfit strain on InP and InGaAs are +1.94% and -1.94%, respectively. Further explanation is requested to confirm if this calculation is correct.
  • #1
msPhysics
5
0

Homework Statement


I would like to calculate the misfit strain on InP and InGaAs when InGaAs is grown on InP


Homework Equations



lattice constants for InP , a1= 5.8687 InGaAs a2=5.7455 ( with 25% In)



The Attempt at a Solution




I have calculated the lattice mismatch ratio as -1.94% , from lattice mismatch = (a2-a1)/a1

I understand that as lattice constant of InGaAs at this composition is smaller than InP InGaAs is under tension and InP is under compression.

I don't know how can I use the lattice mismatch to calculate these strains (compression on InP and tension on InGaAs)

I have read somewhere that misfit strain is just the lattice mismatch ratio with sign change. Is that true?
 
Physics news on Phys.org
  • #2
If yes then misfit strain on InP and InGaAs are +1.94% and -1.94% respectively. I am not sure whether I am doing it correctly or not. Can anyone please explain the concept behind this. Thanks in advance
 

1. How do I determine the misfit strain between two materials?

To calculate the misfit strain between two materials, you need to measure the lattice parameters of both materials and then use the formula: (a1 - a2) / a2, where a1 and a2 are the lattice parameters of the first and second material, respectively.

2. What is the difference between misfit strain and thermal strain?

Misfit strain is the strain that occurs when two materials with different lattice parameters are joined together, while thermal strain is the strain that results from changes in temperature. Misfit strain is a permanent strain, while thermal strain is a temporary strain that can be reversed when the temperature changes.

3. Can misfit strain be negative?

Yes, misfit strain can be negative. This occurs when the lattice parameter of the second material is larger than the first material, resulting in a negative value for the misfit strain. A negative misfit strain can lead to compressive stress and may cause the material to crack or deform.

4. How does misfit strain affect the properties of a material?

Misfit strain can have a significant impact on the properties of a material. It can cause defects in the crystal structure, which can affect the mechanical, electrical, and thermal properties of the material. Misfit strain can also lead to stress and strain in the material, which can influence its overall performance and durability.

5. Is there a way to reduce misfit strain between two materials?

Yes, there are several methods that can be used to reduce misfit strain between two materials. These include choosing materials with similar lattice parameters, using a buffer layer between the two materials, and controlling the growth conditions during the fabrication process. These methods can help minimize the misfit strain and improve the overall quality of the material.

Similar threads

  • Advanced Physics Homework Help
Replies
1
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
3
Views
3K
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Advanced Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
21
Views
6K
  • Engineering and Comp Sci Homework Help
Replies
7
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
4K
  • Mechanical Engineering
Replies
15
Views
3K
Replies
6
Views
2K
Back
Top