> You have n-type material, where the charge carriers are electrons. So far so good (a real particle) Even that: It's a quasi particle. It's an electron with

> You have n-type material, where the charge carriers are electrons. So far so good (a real particle) Even that: It's a quasi particle. It's an electron with an effective mass, which differs from the mass of an electron in free space. The effective mass arises because of the collective electron interaction with the crystal atoms. At a range of high energies, the electron even exhibits the same behavior you'd expect from a relativistic particle (with something different than c for the ultimate velocity.)