Assertion (A): We cannot form a p-n junction diode by taking a slab of a p-type semiconductor and physically joining it to another slab of an n-type semiconductor.
Reason (R): In a p-type semiconductor, \( n_e \gg n_h \) while in an n-type semiconductor \( n_h \gg n_e \).
Evaluation of the assertion and its explanation requires principles of semiconductor physics.
Assertion (A): A p-n junction diode cannot be fabricated by physically joining a p-type semiconductor slab with an n-type semiconductor slab.
Explanation: A p-n junction diode is created by doping a single semiconductor crystal to make one region p-type and the other n-type. This method preserves a continuous crystal lattice and a coherent junction. The physical joining of separate slabs would result in interface defects, a discontinuous crystal lattice, and significant charge carrier recombination at the interface, rendering the diode non-functional. Therefore, the assertion is true concerning the practical requirements for an effective diode, as simple physical joining does not yield a functional diode due to lattice discontinuities.
Reason (R): In a p-type semiconductor, \( n_e \gg n_h \), whereas in an n-type semiconductor, \( n_h \gg n_e \).
Explanation: This statement is factually incorrect. In p-type semiconductors, the majority carriers are holes (\( n_h \)), meaning \( n_h \gg n_e \). Conversely, in n-type semiconductors, the majority carriers are electrons (\( n_e \)), meaning \( n_e \gg n_h \). The given reason presents the opposite of these established relationships.
The correct conclusion is: Assertion (A) is false and Reason (R) is also false.