Advertisements
Advertisements
Question
With reference to semiconductor physics, answer the following question.
In which material “Forbidden band” is absent?
Solution
In the case of a conductor, there is no forbidden gap between the two bands; instead, they overlap. This permits unrestricted electron conduction at all energies, which is a characteristic of conductors.
APPEARS IN
RELATED QUESTIONS
Draw separate energy band diagram for conductors, semiconductors and insulators and
label each of them.
There are energy bands in a solid. Do we have really continuous energy variation in a band ro do we have very closely spaced but still discrete energy levels?
What is the resistance of an intrinsic semiconductor at 0 K?
In a transistor,
The electrical conductivity of pure germanium can be increased by
(a) increasing the temperature
(b) doping acceptor impurities
(c) doping donor impurities
(d) irradiating ultraviolet light on it.
Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.
Let ΔE denote the energy gap between the valence band and the conduction band. The population of conduction electrons (and of the holes) is roughly proportional to e−ΔE/2kT. Find the ratio of the concentration of conduction electrons in diamond to the in silicon at room temperature 300 K. ΔE for silicon is 1.1 eV and for diamond is 6.1 eV. How many conduction electrons are likely to be in one cubic metre of diamond?
The valance of an impurity added to germanium crystal in order to convert it into p-type semiconductor is
The reaction between α and β parameter of a transistor is given by
- Assertion (A): In insulators, the forbidden gap is very large.
- Reason (R): The valence electrons in an atom of an insulator are very tightly bound to the nucleus.