Why do electrons move faster than holes?

As electrons are of lighter mass than holes so their acceleration are more than that of holes which follow drift velocity inside conductor,making electron move much faster.

What affects electron mobility?

Semiconductor mobility depends on the impurity concentrations (including donor and acceptor concentrations), defect concentration, temperature, and electron and hole concentrations. It also depends on the electric field, particularly at high fields when velocity saturation occurs.

Which has higher mobility electron or hole?

The electron mobilty is often greater than hole mobility because quite often, the electron effective mass is smaller than hole effective mass. The relaxation times are often of the same order of magnitude for electrons and holes and therefore, they do not make too much difference.

What does electron mobility depend on?

Why does the mobility of electrons in a semiconductor decreases with increasing donor density?

The doping as impurity affects the the mobility of free carriers in the semiconductor material. As the doping increases the mobility decreases.In addition to the scattering of the electrons by doping atoms, the free carriers will be scattered also by the thermal vibration of the lattice.

Why do holes move slower than electrons?

Holes generally move more slowly than electrons, however, because they function within the tightly bound valence band rather than the conduction band. Ordinary temperatures are not high enough to excite many electrons into the conduction band.

What is the difference between holes and electrons?

Unlike an electron which has a negative charge, holes have a positive charge that is equal in magnitude but opposite in polarity to the charge an electron has. Holes can sometimes be confusing as they are not physical particles in the way that electrons are, rather they are the absence of an electron in an atom.

Why do electrons have higher mobility than holes?

As we have studied that electrons are having higher mobility than holes, however only very few of us know the simplest reason behind this reason. Higher mobility of electrons is the reason behind the preference of npn transistor for high speed applications.

What is meant by the term mobility of electron?

Mobility is the speed (velocity) of movement of a particle (an electron or a hole) per unit Electric field (in low field situations). So this movement of vacancies (hole) is ‘harder’ than the movement of electrons, which are not in bound states.

What is the meaning of hole mobility?

Holes are simply vacancies, they move when electron from one position move to available hole. Thus the hole which was in pos1 is now effectively in pos2…thus we say the hole has “moved”. Thus hole mobility measurement is obviously a measurement of how fast an electron can vacate a position and occupy another.

Why does graphene have different electron and hole mobilities?

One case is graphene where, because of the symmetric band structure, the electron and hole mobilities are the same. Also, it is well documented in the literature and applied universally in industry that adding strain to the channel material correctly can increase mobility.