Question

Write the two examples of acceptor impurities.

Answer 1

Hint: we know that the addition of impurities to a semiconductor material leads to cause variation in the conducting nature of the material. The major factor of difference between donor and acceptor impurities is that a donor impurity donates charges to the semiconductor. Acceptor impurity is the impurity which accepts the charges from the semiconductor material.

Complete answer:
If an acceptor impurity is added to a semiconductor, it can also be a dopant atom which can form a p-type region. These atoms have electrons but four in their outermost shell, and hence they accept electrons from nearby atoms. The examples of such atoms are boron and aluminium.

Additional information:
Therefore acceptor impurity when added to a semiconductor then it accepts the charge from the neighbouring atom of the crystal structure. Donor impurity atom is having a total of 5 electrons in its valence shell. While acceptor impurity is having 3 electrons in its valence shell. Due to the presence of extra electron group V elements of the periodic table are considered donor impurity. Due to the presence of less number of electrons in the valence shell however, group III elements of the periodic table are considered as acceptor impurity.

Note:
When doped with a semiconductor, if a dopant has 3 electrons in its valence shell to raise its conductivity, it is known as an acceptor impurity. It has the ability to accept an electron from a neighbouring atom as it has a vacancy of electron. Thus is called acceptor impurity. P-type region is formed due to the presence of excess positive charge. Therefore the acceptor impurity is used to form p-type semiconductors. Group III elements are the donor impurity as these elements consist of 3 electrons in the valence shell. Thus is known as trivalent impurity. Examples of trivalent impurity are elements like boron, aluminium, indium and gallium.