Question

a pn junction is formed by
select one:
o a. the collision of a proton and a neutron
o b. the recombination of electrons and holes
o c. the boundary of a p - type and an n - type material
o d. ionization

Explanation:

A pn junction is formed at the boundary where p - type (with holes as majority carriers) and n - type (with electrons as majority carriers) semiconductor materials meet. Option a is about nuclear particles (proton and neutron), not related to pn junctions. Option b (recombination of electrons and holes) occurs within the junction but is not what forms the junction. Option d (ionization) is a process in semiconductors but not what forms the pn junction. The key concept is the physical boundary between p - type and n - type materials forming the pn junction.

Answer:

C. the boundary of a p - type and an n - type material