Maharashtra BoardEnglish MediumSTD 11 SciencePhysicsSemiconductors3 Marks
Question
$C, Si$ and $Ge$ have same lattice structure. Why is $C$ insulator while $Si$ and $Ge$ intrinsic semiconductors?
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Answer
$1.$ The $4$ valence electrons of $C, Si$ or $Ge$ lie respectively in the second, third and fourth orbit.
$2.$ Energy required to take out an electron from these atoms $($i.e., ionisation energy $E_g)$ will be least for $Ge,$ followed by $Si$ and highest for $C.$
$3.$ Hence, number of free electrons for conduction in $Ge$ and $Si$ are significant but negligibly small for
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