SaM - Surface Defects & Grain Boundary Barriers

What are Surface Defects and Grain Boundary Barriers:
- Surface Defects are imperfections or irregularities that exist on the surface of a material.
- Due to this Surface Defects, in a non-uniform material (or more specifically a crystal) Grain Boundaries are formed.
- Grain Boundaries are interfaces that separate different crystalline regions or grains within a material.
  When a material is not a continuous crystal but consists of many small crystals or grains, the grain boundaries are where these grains meet.
- Grain Boundaries can act as barriers to various processes and properties in materials.

==You always have surface defects==.

You can represent a surface defect as a difference in energy levels, here you can see a normal intrinsic silicon represented by $E_{C}$ and $E_{V}$ and attached to it an imperfection in the extrinsic silicon, it is represetned as a doped silicon with $E_{A}$ and $E_{D}$ the acceptor energy level and donor energy level.
If we have a surplus or fewer electrons due to the imperfection, an electron will be given/taken from the intrinsic silicon, resulting in the creation of a small localized electric charge.
If the donor level loses the electron, or if they acceptor take the electrons, you have some localized charge at the surface.

The localized charge gives form to an electric field:

🪴 Quartz 4.0