n-type dopant

N-type dopants are donor elements from Group V of the periodic table (phosphorus, arsenic, antimony) that contribute extra electrons to the silicon crystal lattice, creating regions with negative charge carriers essential for forming NMOS transistors, n-wells, and n-type junctions in semiconductor devices. Phosphorus (P) is the most commonly used n-type dopant—moderate mass (31 amu) provides good depth control, high solid solubility (~1×10²¹ cm⁻³ at 1000°C), and relatively fast diffusion enabling deep well and channel implants. Arsenic (As) is preferred for shallow junctions due to its heavy mass (75 amu) which limits implant depth and reduces channeling, with high solid solubility and slow diffusion—ideal for NMOS source/drain extensions at advanced nodes. Antimony (Sb) has the heaviest mass (122 amu) and slowest diffusion of the common n-type dopants—used for buried layers in bipolar transistors and applications requiring minimal dopant redistribution during subsequent thermal processing. Implant energies range from 0.2 keV (ultra-shallow extensions) to 2 MeV (deep retrograde wells). Doses range from 1×10¹² cm⁻² (threshold voltage adjust) to 5×10¹⁵ cm⁻² (heavy source/drain). After implantation, thermal annealing activates dopants onto substitutional lattice sites where they become electrically active donors, each contributing one free electron to the conduction band.