Why cant extrinsic semiconductors be fabricated from bivalent and hexavalent elements?
In N-type semiconductor, pentavalent impurity is added to contribute one electron.... why cant one add an element with six electrons in the outermost shell to contribute two electrons to increase the conductivity?
similarly,
In P-type semiconductor, trivalent impurity is added to contribute one hole.... why cant one add a bivalent impurity to contribute two holes to increase the conductivity?
In N-type semiconductor, pentavalent impurity is added to contribute one electron.... why cant one add an element with six electrons in the outermost shell to contribute two electrons to increase the conductivity?
similarly,
In P-type semiconductor, trivalent impurity is added to contribute one hole.... why cant one add a bivalent impurity to contribute two holes to increase the conductivity?