Q&A

Why does doping decrease mobility?

Why does doping decrease mobility?

At higher doping concentrations, the mobility of electrons and holes decreases with increasing doping concentration due to ionized impurity scattering.

What factors affecting the mobility of charge carriers?

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.

What do you mean by mobility of carrier How does it depend on temperature and doping concentration?

Also was studied the variation of mobility with temperature. At high temperature the mobility decreases, by the lattice atoms, at low temperature the mobility decreases also by ionized impurity. The carrier have a similar doping dependence: for low doping concentration, the mobility is almost constant.

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How does doping affect conductivity of semiconductor?

The conductivity of semiconductors is increased by adding an appropriate amount of suitable impurity or doping. Doping can be done with an impurity which is electron rich or electron deficient as compared to the intrinsic semiconductor, silicon or germanium. Such impurities introduce electronic defects in them.

Why mobility in a doped semiconductor is less than mobility in an intrinsic semiconductor?

Normally the effective mass of electrons is smaller than the effective mass of holes. This why the hole mobility is normally smaller than the electron mobility in crystalline materials.

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.

What are the parameters affecting the mobility?

Significant predictors of mobility included younger age, taking mediation, regular physical activity, female gender, higher income, higher fatigue and better perception on sleep duration, which explained 18\% of the total variance of mobility.

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How mobility depends on the temperature doping concentration ionized atoms and phonons?

They can scatter due to the presence of ionized impurities so higher doping results in lower mobility. They can scatter from the lattice vibrations (called phonons). The population of these increases as temperature increases (the lattice atoms vibrate in more ways as temperature increases).

Does doping decrease conductivity?

The conductivity of a semiconductor material depends on the mobile charge concentration and the mobility. In relatively low oping the carrier concentration increases linearly with doping concentration while the mobility decreases in a lesser extent with doping hence the conductivity increases with the doping.

How does doping affect the mobility of an electron?

Mobility decreases as the doping concentration increases. Mobility is the ability of an electron to move freely under the influence of electric field. In a semiconductor, with the increase of doping, charge carrier concentration increases which leads to the increased probability of charge carrier (electron) collision.

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What is the effect of doping on the semiconductor material?

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.

What is the relationship between temperature and doping levels?

For temperature, the increased temperature increases the number of phonons, which increases the probability that an electron will be scattered by a phonon. For doping levels, each dopant atom is a defect site that an electron can scatter from.

What is the effect of temperature on the mobility of charge carriers?

Increased temperature leads to excessive collisions of charge carriers. In these collisions there are chances that these carriers are trapped in impurity centres. Hence there is a reduction of overall drift of carriers which results in decrease of mobility.