Transistors are made of materials like silicon or germanium that are capable of allowing

electrical current to flow through them in a controlled manner.

The materials of transistors are doped, or “treated,” with

impurities to create a structure called a p-n junction. In this case, “p” stands

for positive and the “n” stands for negative. These notations refer to the

type of dopant atoms (impurities) that have been added to the semiconductor material.