Pentavalent Elements & Doping Semiconductors: Why Not 6 Valence Electrons?

[krishnenduk]

Doping doubt...

Why pentavalent elements are used in doping semiconductors why not an element with 6 valence electrons?

 

[kanato]

Here's a list of <a href="http://en.wikipedia.org/wiki/List_of_semiconductor_materials#Group_II-VI">II-VI semiconductors</a> where elements with 6 valence electrons are used.

Maybe someone who knows more about semiconductors specifically can answer your question, but my guess is that once you get to II-VI semiconductors the band gaps start to become large due to the stronger ionic character relative to III-V's. If the band gap is too large, you wind up with a good insulator or a bad semiconductor.