I am confused about a couple of points:

When the electrons diffuse from N side to P side, and holes diffuse from P side to N side, negative charged region is formed at the junction in P type and positive charged region is formed near the junction in the N type.

The question is:

1. Why is the positive charge not distributed in the entire N type region (as there are free electrons for conduction in the N type region)?
2. Why are the charges fixed at junction despite the presence of holes and free electrons?