Why do Ge and Si are semiconductor?...

Why do Ge and Si are semiconductor?

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In the energy band diagram of Ge and Si. The energy gap is `0.72 eV `and 1.1 eV respectively between conduction band and valence band. As a result of it, they behave as semiconductor.

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Assertion (A) : C,Si and Ge have 4 Valancy each both but C is an insulator where as Si and Ge are semi conductors Reason ( R) : Energy gap is least for Ge , less for Si compared to C , So that free electrons for conduction in Ge and Si are significant but negligible small for C .

`A,R` are true and `R` explains `A` correctly

`A,R` are true and `R` do not explain `A` correctly

`A` is true, but `R` is false

`R` is true, but `A` is false

What is the energy gap in Si semiconductor?

4.4 eV

0.3 eV

0.7 eV

1.1 eV

Si and Ge used for semiconductors are required to be of high purity and hence purified by :

zone–refining

electrorefining

Van–Arkel’s process

cupellation process