Question

Assertion: Group-$13$ doped crystals of Si are called p-type semiconductors.
Reason: Positive holes are responsible for the semiconducting properties.

• A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion
• C. Assertion is correct but Reason is not correct
• D. Assertion is not correct but Reason is correct
• E. Both Assertion and Reason are incorrect

Answer 1

Answer: (A)

Both Assertion and Reason are correct and Reason is the correct explanation of Assertion

The addition of small amount of foreign impurity in the host crystal is called as doping. It results in an increase in the electrical conductivity of the crystal. Doping of group 14 elements (such as Si, Ge etc.) with elements of group 15 (such as As) produces an excess of electrons in the crystals, thus, giving n-type semiconductors. Doping of groups 14 elements with group 13 elements (such as Indium) produces holes (electron deficiency) in the crystals. Thus, p-type semiconductors are produced. The symbol 'p' indicates flow of positive charge. Positive holes are responsible for the semiconducting properties like conduction.