Question

Which of the following deposition conditions favour the formation of larger grains in thin film?

• A. Low deposition rate and low substrate temperature
• B. Low deposition rate and high substrate temperature
• C. High deposition rate and low substrate temperature
• D. High deposition rate and high substrate temperature

Hint:

For thin film deposition, lower deposition rates and higher substrate temperatures promote the formation of larger grains by enhancing atomic mobility and allowing better diffusion on the substrate surface.

Answer 1

The Correct Option is B

The grain size in thin films is influenced by the deposition rate and the substrate temperature.

Step 1: Understanding the factors affecting grain growth.
- A low deposition rate allows for better diffusion of the atoms on the substrate surface, which leads to the formation of larger grains. - A high substrate temperature promotes atomic mobility, allowing atoms to settle in a more stable configuration, which also favors the growth of larger grains.

Step 2: Analyzing the options.
- Option (A) with a low deposition rate and low substrate temperature will result in small grains because the atoms do not have enough energy to diffuse and grow large grains.
- Option (B) with a low deposition rate and high substrate temperature favors the formation of larger grains due to enhanced diffusion and atomic mobility.
- Option (C) with a high deposition rate and low substrate temperature will lead to small grains because the fast deposition limits atomic mobility, preventing large grains from forming.
- Option (D) with a high deposition rate and high substrate temperature might lead to some larger grains, but the fast deposition rate inhibits grain growth.

Step 3: Conclusion.
The correct condition for the formation of larger grains is low deposition rate and high substrate temperature. The answer is (B).

Final Answer: (B) Low deposition rate and high substrate temperature