positive
negative
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
silicon is intrinsic semiconductor until we add some impurities in it. the impurities are either of group 3 called acceptors which make p type or of group 5 called donors which make n type semiconductor.
What happens depends on the temperature coefficient of the diode. If that diode has a positive temperature coefficient, it resistance increases with increased temperature. A diode with a negative temperature coefficient does the opposite.
positive
negative
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.
hall coefficient of a lightly doped semiconductor will decrease with increase in temp as hall coefficient is inversely proportional to number density of charge carriers.
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.
we know that relation in semiconductor is conductivity proportional to temp especially in extrinsic semiconductor holes or electrons are charge carriers . in extrinsic semiconductor when temp is increased then the energy of charge carriers also increases. now kinetic energy equall to [ (1/2) m v^2 ] in this M is constant this implies energy prop to square of velocity therefore if conductivity of charge carriers increases while increasing of temperature
Those semiconductors in which some impurity atoms are embedded are known as extrinsic semiconductors.
...It is due to the fact that at higher temperatures, the energy in the semiconductor is greater than Eg by a considerable amount, meaning that the conduction band is more full. At these high temperatures, the dopants' role on electron-hole pairs is negligible.
the impurity add here is 1 atom of per million atoms of semiconductor.......
The no of electrons in the conduction band increases when the temperature of the semiconductor material increases. therefore resistance decreases. This is also know as "Negative temperature coefficient"
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
Intrinsic diodes are formed by a p-n junction within a single semiconductor material, while extrinsic diodes are formed when impurities are added to a semiconductor material to alter its properties. Intrinsic diodes have natural electrical properties, while extrinsic diodes have controlled electrical properties based on the type and amount of impurities added.