pdopning

pdopning, or p-doping, is the intentional introduction of acceptor impurities into a semiconductor to create p-type material, in which holes are the majority charge carriers. This contrasts with n-type doping, where donor impurities supply extra electrons. By introducing acceptors such as boron or aluminum into silicon, or zinc in certain III-V semiconductors, energy levels are created slightly above the valence band. At room temperature these acceptor levels are ionized, increasing the hole concentration and lowering the material’s resistivity.

Dopant atoms substitute for host atoms in the crystal lattice, and the overall hole density p is approximately equal to the acceptor concentration Na, adjusted by compensation from other impurities. Doping level, temperature, and material determine carrier mobility, with holes generally having lower mobility than electrons. Very high doping can cause degeneracy, where the material behaves more like a metal and the simple drift-diffusion picture changes.

Typical methods to achieve p-doping include diffusion of dopants into silicon, ion implantation followed by thermal annealing, and in epitaxial growth processes (such as chemical vapor deposition or molecular beam epitaxy) by introducing dopant precursors. The choice of technique depends on material, desired depth profile, and device geometry.

P-type layers are essential for many semiconductor devices. In silicon technology, p-doped regions form p-n junctions in diodes and transistors and serve as contacts in various architectures. In optoelectronics, p-type materials are used in LEDs and solar cells alongside n-type layers. The study of p-doping continues to optimize conductivity, junction properties, and compatibility with fabrication processes.