Why conductivity of conductor decreases while semiconductor increases with increasing temperature?
Last updated date: 27th Mar 2023
•
Total views: 276.6k
•
Views today: 7.52k
Answer
276.6k+ views
Hint: When temperature is increased the electrons get more energy. The conductivity of a material depends on the number of charged electrons.
Complete step by step solution:
When temperature is increased in case of a semiconductor the free electron gets more energy to cross the energy gap to the conduction band from the valence band.so now more electrons can go easily to the conduction band so resistance decreases with temperature. But due to temperature increase, in conductors the atoms of the conductor vibrate which gives a resistance to the free electrons. There are two things that affect the resistance. The number of mobile charge carriers (typically electrons or holes) and their mobility (mainly limited due to scattering from atoms).
Conductivity of a material depends on two factors
Number, of electron in conduction band
Collision of conduction electron with core atom. Factor 1 increases conductivity and Factor 2 decreases.
Additional information:
The big difference between the two materials is the band gap of the semiconductor. Electrons in the semiconductor that do not have sufficient energy cannot contribute to the conductivity. Therefore, increasing the energy of the electrons, increases the number of electrons or holes (charge carriers) that can contribute to the conductivity, thereby drastically lowering the resistance. This effect does not occur in metals.
Note: Because the latter effect is typically much bigger than the first, even though there is an increase of scattering at higher temperatures, the resistance of semiconductors decreases with increasing temperature. When you increase the temperature both the electrons and the atoms will obtain more energy. This holds for both a regular metallic conductor and for a semiconductor. Both materials will see an increase in scattering of electrons from the increasingly vibrating atoms.
Complete step by step solution:
When temperature is increased in case of a semiconductor the free electron gets more energy to cross the energy gap to the conduction band from the valence band.so now more electrons can go easily to the conduction band so resistance decreases with temperature. But due to temperature increase, in conductors the atoms of the conductor vibrate which gives a resistance to the free electrons. There are two things that affect the resistance. The number of mobile charge carriers (typically electrons or holes) and their mobility (mainly limited due to scattering from atoms).
Conductivity of a material depends on two factors
Number, of electron in conduction band
Collision of conduction electron with core atom. Factor 1 increases conductivity and Factor 2 decreases.
Additional information:
The big difference between the two materials is the band gap of the semiconductor. Electrons in the semiconductor that do not have sufficient energy cannot contribute to the conductivity. Therefore, increasing the energy of the electrons, increases the number of electrons or holes (charge carriers) that can contribute to the conductivity, thereby drastically lowering the resistance. This effect does not occur in metals.
Note: Because the latter effect is typically much bigger than the first, even though there is an increase of scattering at higher temperatures, the resistance of semiconductors decreases with increasing temperature. When you increase the temperature both the electrons and the atoms will obtain more energy. This holds for both a regular metallic conductor and for a semiconductor. Both materials will see an increase in scattering of electrons from the increasingly vibrating atoms.
Recently Updated Pages
Most eubacterial antibiotics are obtained from A Rhizobium class 12 biology NEET_UG

Salamin bioinsecticides have been extracted from A class 12 biology NEET_UG

Which of the following statements regarding Baculoviruses class 12 biology NEET_UG

Sewage or municipal sewer pipes should not be directly class 12 biology NEET_UG

Sewage purification is performed by A Microbes B Fertilisers class 12 biology NEET_UG

Enzyme immobilisation is Aconversion of an active enzyme class 12 biology NEET_UG

Trending doubts
Difference Between Plant Cell and Animal Cell

Write an application to the principal requesting five class 10 english CBSE

Ray optics is valid when characteristic dimensions class 12 physics CBSE

Give 10 examples for herbs , shrubs , climbers , creepers

Write the 6 fundamental rights of India and explain in detail

Write a letter to the principal requesting him to grant class 10 english CBSE

List out three methods of soil conservation

Fill in the blanks A 1 lakh ten thousand B 1 million class 9 maths CBSE

Write a letter to the Principal of your school to plead class 10 english CBSE
