Impurities in Semiconductor

The addition of a small percentage of impurities (foreign atoms) in the **regular crystal lattice** of silicon produces changes in their electrical properties. **N-type** and **P-type** semiconductors are produced by this processing. Impurity atoms with **five** valence electrons produce **n-type semiconductors** by contributing extra electrons. Impurity atoms with **three** valence electrons produce **p-type semiconductors** by producing a hole. The impurity atoms can fill empty places in the **crystal lattice** which are always present. Another possibility is the **inter lattice diffusion**. Here are impurity atoms moved in-between the **silicon atoms** in the crystal lattice. The impurity atoms could be located in the crystal lattice like **exchanged atoms** with the **silicon atoms**.