# What is the formation energy of a defect? What does it mean in physics?

• smokefly
In summary: Thanks a lot for the clear image. It helps a lot.In summary, the formation energy of a defect in a semiconductor is the difference in total crystal energy before and after the defect arises. It represents the cost of broken atomic bonds and lattice stress, but is offset by an increase in entropy due to the defect.
smokefly
I am reading some theoretical papers on the defects in semiconductors. Theorists can calculate the formation energy of a certain kind of defect. If the number is too big, this defect is very unlikely to be seen. So what does this “formation energy” mean? Is that the energy necessary to move atoms together to form this defect, which is also the energy necessary to keep the defect structure from dissociating? That's my understanding but I don't know if it is correct or not.

The formation energy is the difference in the total crystal energy before and after the defect arises. It represents the penalty in broken atomic bonds and in lattice stress. Opposing this energy penalty, however, is the increase in entropy because a crystal containing a defect has more possible microstates than a perfect crystal. Does this help?

Thanks a lot for the clear image. It helps a lot.

Mapes said:
The formation energy is the difference in the total crystal energy before and after the defect arises. It represents the penalty in broken atomic bonds and in lattice stress. Opposing this energy penalty, however, is the increase in entropy because a crystal containing a defect has more possible microstates than a perfect crystal. Does this help?

## What is the formation energy of a defect?

The formation energy of a defect is a measure of how much energy is required to create a defect in a material. It is typically expressed in units of electron volts (eV) per atom and is used to quantify the stability of defects in a material.

## What factors affect the formation energy of a defect?

The formation energy of a defect is influenced by several factors, including the type and size of the defect, the composition of the material, and the surrounding environment. Additionally, external factors such as temperature and pressure can also impact the formation energy of a defect.

## How is the formation energy of a defect calculated?

The formation energy of a defect is typically calculated using theoretical models and computer simulations, such as density functional theory (DFT). These methods take into account the atomic and electronic structure of the material to determine the energy required to create a defect.

## What does the formation energy of a defect tell us about a material?

The formation energy of a defect provides important information about the stability and properties of a material. Higher formation energies indicate that defects are less likely to form, while lower formation energies suggest that defects may be more prevalent and can have a significant impact on the material's behavior and performance.

## How does the concept of formation energy of a defect relate to physics?

The concept of formation energy of a defect is rooted in the principles of thermodynamics and quantum mechanics. It involves understanding the energy levels and interactions of atoms in a material and how they can be altered by the presence of a defect. This knowledge is crucial for predicting and manipulating the behavior of materials in various physical and chemical processes.

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