P-type Semiconductor
An extrinsic semiconductor in which trivalent acceptor impurities create an excess concentration of positive holes as majority charge carriers.
Governing formula
p ≈ N_A ≫ n, n p = n_i²
SI unit
cm⁻³ (Hole Concentration)
In depth
Doping silicon (valence 4) with trivalent atoms like Boron (valence 3) leaves an unfilled electron bond. Thermal energy easily promotes a valence electron into this acceptor level (E_a), creating a mobile hole in the valence band.
Examples in the real world
Boron-doped silicon forming the p-layer of p-n junction solar cells and LEDs.