Creation of Electron Hole pairs in a
Si crystal
Electron Hole pairs in a Si crystal
Types of current in a pure
Semiconductor
 Electron Current
 Hole Current
Electron Current
 In Intrinsic Si, it is produced by the movement of
thermally generated free electrons
Hole Current in Intrinsic Si
Extrinsic Semiconductors
 Two Types
1. N type Semiconductors
2. P type Semiconductors
N Type Semiconductor
Pentavalent Impurity Atom in a Si Crystal Structure
N Type Semiconductor
P Type Semiconductor
Trivalent Impurity Atom in a Si Crystal Structure
P Type Semiconductor
N type & P type Semiconductors
Effect of donor impurities on the
Energy Band Structure
Effect of Acceptor impurities on
the Energy Band Structure
Change in the Energy band diagram
due to doping
Effect of Temperature on
Semiconductor
Intrinsic Semiconductor
✓ As temp
, more electron-hole pairs are
produced
✓ Conductivity increases with increase in temp
✓ That is resistivity decreases with increase in temp
✓ Hence Semiconductors have –ve temp coefficient
of resistance
Current Flow Information
Current Flow Information