Question

Due to diffusion of electrons from $n$ to $p$-side
I. electron hole combination across $p-n$ junction occurs.
II. an ionised acceptor is left in the p-region.
III. an ionised donor is left in the n-region.
IV. electrons of $n$-side comes to $p$-side and electron hole combination takes place in p-side
Select the correct option from the following.

• A. I and II
• B. II and III
• C. II and IV
• D. I, III and IV

Answer 1

Answer: (D)

When an electron diffuses from $n\to P$, it leaves behind an ionised donor (species which has becomes ion by donating electron) on $n$-side. This ionised donor (positive charge) is immobile as it is bonded to the surrounding atoms. As the electrons continue to diffuse from $n$-P, a layer of positive charge (or positive space-charge region) on $n$-side of the junction is developed. On P-side atom receiving electrons is ionised acceptor.