Advertisements
Advertisements
Question
Answer in detail.
Distinguish between intrinsic semiconductors and extrinsic semiconductors.
Solution
| Sr. No. | Intrinsic semiconductors | Extrinsic semiconductors |
| i. | A pure semiconductor is known as intrinsic semiconductors. | The semiconductor, resulting from mixing of impurity in it, is known as extrinsic semiconductors |
| ii. | Their conductivity is low at room temperature | Their conductivity is high even at room temperature. |
| iii. | Its electrical conductivity is a function of temperature alone. | Its electrical conductivity depends upon the temperature as well as on the quantity of impurity atoms doped in the structure. |
| iv. | The number density of holes (nh) is the same as the number density of free electron (ne) (nh = ne). |
The number density of free electrons and the number density of holes are unequal. |
APPEARS IN
RELATED QUESTIONS
In an intrinsic semiconductor the energy gap Egis 1.2 eV. Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at 600K and that at 300K? Assume that the temperature dependence of intrinsic carrier concentration niis given by
`"n"_"i" = "n"_0 exp(- "E"_"g"/(2"k"_"BT"))`
where n0 is a constant.
Let np and ne be the numbers of holes and conduction electrons in an extrinsic semiconductor.
Let nh and ne be the number of holes and conduction electrons respectively in a semiconductor. Then ______.
In a semiconductor, the number of holes and number of free electrons are represented as 'nh' and 'ne' respectively. Which one of the following statements is TRUE for the semiconductor?
In a pure or intrinsic semiconductor, valence band holes and conduction-band electrons are always ______.
Explain the following term:
Intrinsic semiconductor
An intrinsic semiconductor has a resistivity of 0.50 Ω m at room temperature. Find the intrinsic carrier concentration if the mobilities of electrons and holes are 0.39 m2V-1S-1 and O.11 m2 v-1S-1 respectively:
Hole is ______.
Two crystals C1 and C2, made of pure silicon, are doped with arsenic and aluminium respectively.
Why is doping of intrinsic semiconductors necessary?
What is meant by doping of an intrinsic semiconductor?
Name the two types of atoms used for doping of Ge/Si.
A pure semiconductor has equal electron and hole concentration of 1016 m-3. Doping by indium increases nh to 5 × 1022 m-3. Then, the value of ne in the doped semiconductor is ______.
Answer the following giving reasons:
Impurities are added to intrinsic semiconductors.
- Assertion (A): The resistance of an intrinsic semiconductor decreases with an increase in its temperature.
- Reason (R): The number of conduction electrons as well as hole increase in an intrinsic semiconductor with the rise in its temperature.
