Question

During the formation of $p-n$ junction,

• A. holes diffuse from $p-$side to $n-$side ($p\to n$)
• B. electrons diffuse from $p-$side to $n-$side ($p\to n$)
• C. electrons diffuse from $n-$side to $p-$side ($n\to p$)
• D. holes diffuse from $n-$side to $p-$side ($n\to p$)

Answer 1

Answer: (A), (C)

The correct options are
A holes diffuse from $p-$side to $n-$side ($p\to n$)
C electrons diffuse from $n-$side to $p-$side ($n\to p$)

When a p-n junction is formed, i.e. p-type semiconductor is in contact with the n-type semiconductor, the concentration of holes is higher on p-side than on n-side of p-n junction whereas the concentration of electrons is higher on n-side than on p-side of the junction.
As a result, holes will diffuse from p-side to n-side through junction and electrons will diffuse from n-side to p-side through the junction.