which of the following can be added as an impurity to a semiconductor material to create an n-type semiconductor?
Which of the following can be added as an impurity to a semiconductor material to create an n-type semiconductor?
Answer:
To create an n-type semiconductor, you need to add an element that introduces more free electrons into the semiconductor material. The elements commonly used for this purpose are those from Group V of the periodic table because they have five valence electrons. When one of these elements is introduced into a Group IV semiconductor like silicon (Si) or germanium (Ge), one of its five valence electrons is left unbound, becoming a free electron that can conduct electrical current.
1. Group V Elements:
- Elements such as phosphorus (P), arsenic (As), and antimony (Sb) are typically used. These elements are known as pentavalent impurities because they have five valence electrons.
Detailed Explanation:
- Phosphorus (P):
- Adding phosphorus to silicon (Si) or germanium (Ge) introduces an additional electron because phosphorus has five valence electrons, compared to silicon’s four. This extra electron becomes a free charge carrier, increasing the material’s conductivity.
\text{Si} + \text{P} \rightarrow \text{n-type semiconductor}
- Arsenic (As):
- Similar to phosphorus, arsenic, with five valence electrons, adds one free electron to the silicon lattice when introduced, resulting in an n-type semiconductor.
\text{Si} + \text{As} \rightarrow \text{n-type semiconductor}
- Antimony (Sb):
- Antimony also fits the criteria, introducing an extra free electron into the silicon structure, thus again creating an n-type semiconductor.
\text{Si} + \text{Sb} \rightarrow \text{n-type semiconductor}
Final Answer:
Elements from Group V, like phosphorus (P), arsenic (As), and antimony (Sb), can be added as impurities to a semiconductor material to create an n-type semiconductor.