Key Semiconductor Defects

Semiconductor defects are crucial for understanding how materials behave. These imperfections, like vacancies and interstitials, can change electrical and thermal properties, impacting everything from conductivity to mechanical strength. Recognizing these defects helps improve semiconductor performance in devices.

1. Point defects

   • Localized disruptions in the crystal lattice structure.
   • Can significantly affect electrical and thermal properties.
   • Types include vacancies, interstitials, and substitutional impurities.

2. Vacancies

   • Missing atoms in the crystal lattice.
   • Increase the diffusion rate of atoms and impurities.
   • Affect the material's mechanical and electrical properties.

3. Interstitials

   • Atoms that occupy spaces between the regular lattice sites.
   • Can introduce strain in the lattice and alter conductivity.
   • Often smaller atoms, like hydrogen or carbon, fit into these sites.

4. Substitutional impurities

   • Foreign atoms replace host atoms in the lattice.
   • Can modify the electronic properties and band structure.
   • Commonly used for doping to enhance semiconductor performance.

5. Frenkel defects

   • A combination of a vacancy and an interstitial defect.
   • An atom leaves its lattice site and occupies an interstitial position.
   • Common in ionic crystals and affects ionic conductivity.

6. Schottky defects

   • Pairs of vacancies in cation and anion sublattices.
   • Maintain charge neutrality in ionic compounds.
   • Influence the material's density and electrical properties.

7. Line defects (dislocations)

   • One-dimensional defects that disrupt the regular arrangement of atoms.
   • Crucial for understanding plastic deformation in materials.
   • Can significantly affect mechanical strength and ductility.

8. Edge dislocations

   • Formed by an extra half-plane of atoms in the crystal structure.
   • Movement of edge dislocations allows for slip and deformation.
   • Influence the yield strength and hardness of materials.

9. Screw dislocations

   • Result from a helical arrangement of atoms around a central line.
   • Allow for easier movement compared to edge dislocations.
   • Important in the study of crystal growth and deformation.

10. Planar defects

    • Two-dimensional defects that disrupt the crystal structure.
    • Include grain boundaries, stacking faults, and twin boundaries.
    • Affect the mechanical and electrical properties of materials.

11. Grain boundaries

    • Interfaces between different crystalline regions in a material.
    • Can impede dislocation motion, affecting strength and ductility.
    • Influence electrical properties and diffusion processes.

12. Stacking faults

    • Occur when there is an error in the stacking sequence of atomic planes.
    • Can affect the mechanical properties and slip behavior of materials.
    • Important in the study of crystal growth and phase transitions.

13. Twin boundaries

    • Symmetrical boundaries that separate two mirror-image crystal regions.
    • Can enhance ductility and toughness in materials.
    • Play a role in the deformation mechanisms of metals.

14. Bulk defects (volume defects)

    • Three-dimensional defects that can affect the overall material properties.
    • Include voids and precipitates that can alter mechanical strength.
    • Important in the context of material processing and performance.

15. Voids

    • Empty spaces within the material that can affect density and mechanical properties.
    • Can act as stress concentrators, leading to failure.
    • Influence the diffusion of atoms and impurities.

16. Precipitates

    • Small clusters of atoms that form within a solid matrix.
    • Can strengthen materials through mechanisms like precipitation hardening.
    • Affect the electrical and thermal conductivity of semiconductors.

17. Deep-level traps

    • Defects that can capture charge carriers, affecting conductivity.
    • Often associated with impurities or structural defects.
    • Can lead to recombination of electrons and holes, impacting device performance.

18. Shallow-level dopants

    • Impurities that introduce energy levels close to the conduction or valence band.
    • Enhance the electrical conductivity of semiconductors.
    • Commonly used in doping processes to tailor material properties.

19. Dangling bonds

    • Unpaired bonds at the surface or within the material.
    • Can act as traps for charge carriers, affecting surface conductivity.
    • Important in the context of surface states and reactivity.

20. Surface states

    • Electronic states that exist at the surface of a material.
    • Can influence the electrical properties and reactivity of semiconductors.
    • Important for understanding phenomena like surface conductivity and adsorption.