PPT Slide

53

• When silicon is doped with phosphorus, the extra valence electron  in each P atom is free to move into the silicon conduction band.

n-type semiconductor

Si valence band

Si conduction band

• When silicon is doped with gallium, Ga atoms, with 1 fewer valence electrons than Si, introduce a positive ìholeî into the Si valence band.

Si conduction band

Si valence band

p-type semiconductor

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