Question

The mobility of free electrons is greater than that of free holes because?

Answer 1

Hint: In semiconductor materials, the two types of charge carriers responsible for current are holes and electrons. In an atom, a hole is the absence of an electron in a specific location. A hole can be transferred from atom to atom in a semiconductor material, despite the fact that it is not a physical particle in the same way as an electron.

Complete answer:
The electrical mobility of charged particles in a fluid under an applied electric field is known as electron and hole mobility.
When an electric field $ E $ is applied over a piece of material, the electrons move at an average velocity known as the drift velocity, $ {v_d} $ . The electron mobility is $ \mu $ then described as follows:
 $ {v_d} = \mu E $
Electrons need less energy to move because they encounter less resistance during their motion than holes.
We can also say that, the electron effective mass is often smaller than the hole effective mass, electron mobility is often greater than hole mobility.
To increase the speed of a system, one must choose materials with small electron and hole effective masses and long relaxation times, i.e., where electrons and holes do not have to collide with crystal imperfections, impurities, etc., i.e., materials with high crystal consistency.

Note:
The energy is not converted into heat energy or thermal vibrations when an electron and a hole interact and recombine. Instead, the energy is converted into a conduction band electron, which is then promoted to a higher energy level in the band.