some questions

• why are impurities added to a pure semiconductor
• are semiconductors crystalline or amorphous?
• what is conductivity
• how are two semiconductors joined? or how is a junction physically formed?
• what is biasing?
• why is biasing needed?
• what is transistor?
• full form of transistor
• why is it called so?
• what is q-point?

These are some basic questions most of the people ask in viva and other interviews so make sure you know them first.