HFC
• Solid material divide into three classes: Conductor, Semiconductor and Insulator
• Conductor has two type band:
Type I conduction band half occupied by electrons
Type II conduction-valence band has overlapped, electrons can’t occupy all the band
• Semiconductor band:
There is a energy gap between conduction & valence band, the gap is smaller
• Insulator band:
The Gap is so large that electron can’t be excited by thermal from valence to conduction band
Conductor Semiconductor Insulator
Conduction band electron half filled
Conduction-Valence band overlap
Valence band
with a few holes
Conduction band
with a few electrons
Empty Conduction Band
Full occupied Valence Band
Eg ~ 1eV
Eg ~ 9 eV
Semiconductor Material
