are called dopants
Doping a semiconductor provides additional charge carriers to the material. The dopant atoms are easily ionized, and this provides the semiconductor with either free electrons in the conduction band or electron vacancies (or holes) in the valence band, both of which allow the semiconductor to conduct electricity.
Semiconductors: When temperature increases, more electrons jump to conduction band from valance bond. Hence resistance decreases. Metals: Already plenty of electrons are there in conduction band. When temperature increases, the electrons in conduction band of metal vibrate and collide each other during their journey. Hence the the resistance of metal increases with increase of temperature. S.Lakshminarayana
at higher values of temperature the intrinsic carrier concentration become comparable to or greater than doping concentration in extrinsic semiconductors. thus majority and minority carrier concentration increases with increase in temperature and it behaves like intrinsic semiconductor.
NO. In a semiconductor the resistance decreases with increase of temperature. It is their natural behavior unlike conductors and insulators. If we decrease the temperature their resistance increases. At 0 degree kelvin all semiconductors will act like perfect insulators.
It is called as DOPING. Doping is the process in which you add an impurity to a pure semiconductor to increase its conductivity. While doping is done, crystal structure of semiconductor is not disturbed.
Doping a semiconductor provides additional charge carriers to the material. The dopant atoms are easily ionized, and this provides the semiconductor with either free electrons in the conduction band or electron vacancies (or holes) in the valence band, both of which allow the semiconductor to conduct electricity.
Semiconductors: When temperature increases, more electrons jump to conduction band from valance bond. Hence resistance decreases. Metals: Already plenty of electrons are there in conduction band. When temperature increases, the electrons in conduction band of metal vibrate and collide each other during their journey. Hence the the resistance of metal increases with increase of temperature. S.Lakshminarayana
The conductivity depends on the passage of charged particles especially electrons. In metals electrons are easily available in conduction band and so its conductivity is high. As we increase the temperature then core of atoms vibrate largely. So with positive charge it could easily minimize the electrons in the conduction band and hence fall in conductivity In case of semiconductor there will be usually forbidden gap between valence band and conduction band. So conduction is poor at ordinary temperature. But as we increase temperature that would allow electrons to reach conduction band as covalent bonds get broken. Hence higher conductivity
With the increase in temperature, the concentration of minority carriers starts increasing. Eventually, a temperature is reached called the critical temperature (85° C in case of germanium and 200° C in case of silicon) when the number of covalent bonds that are broken is very large and the number of holes is approximately equal to number of electrons. The extrinsic semiconductor now behaves essentially like an intrinsic semi-conductor.
With the increase in temperature if the resistance increases or the current in the circuit decreases then it is said to be have positive temperature coefficient .But in semi-conductors with the increase in temperature the electrons present in the valance band are excited and they would enter the conduction band for conduction . As the no. of charge carriers always increase in a semi-conductor , implies that the current always increases with the increase in temperature so the semi-conductor can never have positive temperature coefficient
When a body is conducting, its mobility of ions( valence) is responsible for conduction. As mobility increase, conduction increase. That's why falling temperature reduce it and rising temperature increase it.
Doping a semiconductor means to introduce impurities to the semiconductor in order to alter it. For the most part, doping a semiconductor increases its conductivity.
conductivity of semiconductors increases with increase in temperature as breakdown of covalent bonds take place in the semiconductor due to increase in temp but more & more increase in the temp may result in the breakdown or damage of the semiconductor which results in the decrease in conductivity of semiconductor
Increase
increase conduction of heart
if we increase the temp so large no of electrons jumbs from valence energy band to conduction energy band .when there are alarge no of electrons in conduction band to the conduction increase means this simiconductor can conduct easyly. thanx Engr Bashir Khan.
At absolute zero (0K), an intrinsic semiconductor will act like a perfect insulator. At this temperature, the electrons in the valence band will remain there. The heat energy required to excite the electrons from the valence band to the conduction band is insufficient at 0K. When the temperature increases, some of the electrons from the valence band got excited and moves to the conduction band. This will give rise to the conductivity of the semiconductor. i.e in 0 k(0 kelvin) the pure semi conductor the electrons in the valance band don't do any thing.They are lazy for conductivity.But when increasing the temperature increase the energy of electrons and they try to move.At the end electrons win and they can to move.So it happened a conductivity.