Energy levels for isolated impurities in silicon measured from the nearest band edge in electron volts. Donors are indicated with a plus charge and acceptors with a minus charge, their charges after ionization leading to conduction-band electrons and valence-band holes.
Adapted from Streetman, B. G. Solid State Electronic Devices, 3rd ed.; Prentice Hall: Englewood, NJ, 1990; p 108