FORWARD BAIS & REVERSE BAIS

If a battery is connected across a P - N junction with its positive terminal joined to the N - type side and its negative terminal to the p type side, it helps the junction voltage and the junction is said to be REVERSED BAISED. Electrons and holes are repelled further from the junction and the depletion layer winds only a few thermally generated minority carrier cross the junction and a very small current, called reverse current or leakage flows. If a battery is connected across a P - N junction with its positive terminal joined to the P - side and its negative terminal to the N - type side, it opposes the junction voltage and the junction is said to be FORWARD BAISED. Because of the forward baised the depletion layer narrows. When the the battery voltage exceeds the junction voltage and appreciable current flows because majority charge carrier are able to cross the junction, the electrons from N - type side to P - type side and holes in the opposite direction.
In brief a junction conducts when it is forward baised and no current flows through it when it is reversed baised.