a p-type semiconductor

A p-type semiconductor is one doped so that its current is carried mainly by positive holes — the 'p' stands for positive. You make it by adding acceptor atoms, each of which is one electron short of completing its bonds and therefore creates a hole. The crystal ends up full of mobile holes, which conduct current as if they were positive particles drifting through the material.

The recipe mirrors n-type. Silicon has 4 valence electrons per atom. Drop in a boron atom (group III, only 3 valence electrons) at a silicon site — it can only complete three of the four bonds, leaving one bond one electron short. That missing electron is a hole. A neighboring valence electron easily hops over to fill it, but in doing so it leaves a hole where it came from, so the hole effectively moves. Because these acceptor-made holes vastly outnumber the thermal electron-hole pairs, holes are the majority carriers and electrons the minority carriers. The Fermi level shifts DOWN, toward the valence band.

p-type is the necessary partner to n-type: joining the two makes the p-n junction that underlies every diode and transistor. Same honesty as before: a block of p-type silicon is electrically neutral, not positively charged. The mobile holes are balanced by fixed negative boron ions (each boron grabbed the extra electron it needed and became a negative ion). Boron, aluminum, and gallium are the common acceptors for silicon. A hole is a bookkeeping device — really it is many electrons shuffling — but treating it as a single positive carrier makes the physics far easier and is completely valid.