What are n type and p-type semi conductors how is a semiconductor junction formed.

N-type semiconductor: If pentavalent impurities are added to pure form of semiconductors, it is called N- type semiconductor
p-type semiconductor : If trivalent impurities are added to pure form of semiconductor, it is called p-type semiconductor .
Formation of semiconductor junctions :

1) If P-type and N-type semiconductors are combined, a junction is formed with two electrodes called P-N junction diode
2) If P-N junction is formed, some of holes in P-type and electrons in N-type are diffused towards each other and recombine
3) Due to this, a narrow region is formed on either side of junction is called "Depletion Region"