Doping

1. Doping is a process of adding a certain amount of specific impurities to semiconductors to increase their conductivity
2. Two types of doping:

• p-type semiconductors
• n-type semiconductors

p-type semiconductors

1. Si (pure/ intrinsic semiconductor) have valency of 4

2. Al (impurity) have four e valens

3. When Al is added to Si, there will be one less e - p-type semiconductor is produced
4. No. of e > No. of holes

n-type semiconductors
1. Si (pure/ intrinsic semiconductor) have valency of 4

2. P (impurity) have three e valens

3. When P is added to Si, there will be one extra e - n-type semiconductor is produced

4. No. of holes > No. of e