Intrinsic Semiconductor
An ultra-pure semiconductor crystal containing no significant dopant impurity species, where carrier concentration is determined purely by thermal excitation across the band gap.
Governing formula
n = p = n_i = √(N_c N_v) e^(-E_g / (2 k_B T))
SI unit
cm⁻³ (Carrier Density)
In depth
Because thermal excitation generates conduction electrons and valence holes in pairs, electron concentration n equals hole concentration p. Electrical conductivity increases exponentially with rising temperature.
Examples in the real world
Ultra-pure monocrystalline silicon wafers manufactured for high-precision scientific radiation detectors.