What does electron mobility depend on?

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.

Why is mobility directly proportional to charge?

Mobility is defined at the velocity of the electron per unit electric field. It is the ease with which the electrons can travel in a conductor. So, the mobility of the electrons is directly proportional to the relaxation time of the electron. This is the required solution.

What is mobility of free electrons in a conductor?

Mobility of electrons in a conductor is defined as the magnitude of the drift velocity per unit electric field.

What is the formula of electron mobility?

The measurement of how fast an electron can move through a semiconductor or a metal which is under the influence of an external electric field is known as electron mobility. We can show electron mobility mathematically by the equation, μ=VdE .

How does the mobility of electrons in a conductor change?

The mobility of charge inside conductor is defined as the ratio of drift velocity of charge per unit of electric field. Mobility is independent of potential difference. So there is no change in mobility of electrons if the potential difference is changed keeping the length and temperature constant.

Why does the mobility of electrons in 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 is the mobility of free electrons greater than that of holes?

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.

How does mobility of electrons in a conductor change?

If potential difference across the conductor is doubled, keeping the length same, the mobility of electrons in the conductor will be doubled. Potential difference is directly proportional to current flowing through the conductor. It means current is equal to the charges flowing through the conductor per unit time.

How does mobility depend on conductivity?

Conductivity is proportional to the product of mobility and carrier concentration. For example, the same conductivity could come from a small number of electrons with high mobility for each, or a large number of electrons with a small mobility for each. Therefore mobility is relatively unimportant in metal physics.

Does mobility depend on potential difference?

And also mobility is independent of potential difference. So there is no change in mobility of electrons if the potential difference is changed keeping the length and temperature constant.

How does mobility change with temperature?

Mobility μ decreases with temperature because more carriers are present and these carriers are more energetic at higher temperatures. Each of these facts results in an increased number of collisions and μ decreases.

Why is the mobility of an electron in the conduction band of a semiconductor more than the mobility of hole or electron in valence band?

Answer: Free electrons, those are moving from one atom to another are in conduction band. Conduction band is at higher energy level than valance band. Hence electron at Conduction band moves faster and has more mobility than holes in valance band.