When arsenic is added as an impurity to silicon,the resulting material is [1996]a)n-type semiconductorb)p-type semiconductorc)n-type conductord)insulatorCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

Arsenic is pentavalent, therefore when added with silicon it leaves one electron as a free electron. In this case the conduction of electricity is due to motion of electrons, so the resulting material is n-type semiconductor.

Answer

When group 15 element(As) is added to a group 13 element(Si), the conductivity of group 13 element increases. The type of semiconductor formed here is n type semiconductor

Answer

Arsenic as an Impurity in Silicon

When arsenic is added as an impurity to silicon, the resulting material is an n-type semiconductor. This phenomenon occurs due to the process of doping, where impurities are intentionally added to semiconductor materials to alter their electrical properties.

Doping in Semiconductors
Doping is a crucial process in semiconductor technology that involves adding impurities to a pure semiconductor material. The impurities used are typically atoms of elements from Group III or Group V of the periodic table. These impurities introduce excess electrons (n-type) or electron deficiencies (p-type) in the semiconductor lattice.

Arsenic as an Impurity
Arsenic (As) belongs to Group V elements, also known as pentavalent elements. When arsenic atoms are added as impurities to silicon (Si), which is a Group IV element, they introduce extra electrons into the silicon lattice. This is because arsenic has five valence electrons, while silicon has only four. The extra electron from the arsenic atom is loosely bound and can easily move around the silicon crystal structure.

N-type Semiconductor
The addition of arsenic impurities increases the number of free electrons in the silicon crystal lattice. These electrons are responsible for the conduction of electric current. As a result, the silicon material doped with arsenic becomes an n-type semiconductor.

In an n-type semiconductor, the majority charge carriers are electrons, while the minority charge carriers are holes (electron deficiencies). The concentration of free electrons in the n-type semiconductor is much higher compared to the concentration of holes.

Working of N-type Semiconductor
In an n-type semiconductor, when a voltage is applied across the material, the excess electrons are free to move and contribute to the flow of current. The electrons move from the negatively charged region (cathode) to the positively charged region (anode), creating an electric current.

The presence of arsenic impurities in silicon allows for better conductivity and enhances the overall performance of semiconductor devices. This is why arsenic-doped silicon is widely used in various electronic applications, such as transistors, diodes, and integrated circuits.

Overall, when arsenic is added as an impurity to silicon, the resulting material becomes an n-type semiconductor due to the introduction of excess electrons into the silicon crystal lattice.

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