Carbon , silicon and germanium have four valence elcectrons each . These are characterised by valence and conduction bands separated by energy band - gap respectively equal to ` (E_g)_(c) (E_g)_(si) ` and ` (E_g)_(Ge) `. Which of the following statements ture ?

Options

A. `(E_(g))_(Si) lt (E_(g))_(Ge) lt E_(g))_(C )`
B. `(E_(g))_(C ) lt (E_(g))_(Ge) gt E_(g))_(Si)`
C. `(E_(g))_(C ) gt (E_(g))_(Si) gt E_(g))_(Ge )`
D. `(E_(g))_(D ) = (E_(g))_(Ge) = E_(g))_(Si)`

Answer

C

Explanation

(c ) Here, carbon has the highest resistivity and germanium has the lowest resistivity.
`:.` Carbon has lowest conductivity and germanium has highest conductivity. So, carbon has highest band gas energy and germanium has lowest band gap energy.