So, here is my answer:
For zero applied voltage (pn junction in equilibrium), you need to know on how:
1. to calculate the built-in potential barrier.
2. to calculate the width of depletion region in n-type and p-type
3. to calculate the maximum electric field
and all the theories under this topic (eventhough as i have mentioned in class, all questions for pn junction will be calculatian type :D)
