questions and answers on semiconductor doping

why silicon doped with arsenic forms a p-type semiconductor

silicon doped with arsenic, arsenic can exist as an atom with valency of 5 or 3, when it  has a valency of 5 it is a pentavalent element and when used as a doping material for semiconductor it will produce an  n-type semiconductor.

 when an atom of arsenic has a valency of 3 , it is a trivalent atom and when used as a dopant  to make extrinsic semiconductors it creates a p-type semiconductor.

explain what happens when germanium doped with antimony n-type or p-type

antimony has 5 electrons in its outermost shell, therefore it is a peentavalent  atom. when used as a doping material it will create an n-type semiconductor because of its excess electrons. therefore  the germanium emiconductor will be an  n-type .

p-type  or n –type when  silicon doped with gallium n-type or p-type

gallium has 3 electron in its outermost electronic shell, it is a trivalent element. when used as a dopant in a semiconductor it will create a p-type semiconductor, outermost shell of gallium is almost empty with three electrons seeking 5 to be complete  while silicon has 4 electrons seeking 4 to be complete with the presence of gallium it will make silicon more electropositive and hence creating holes.

what type is produced when silicon doped with boron and phosphorus

silicon doped with phosphorous  will create an n-type semiconductor . phosphorous is a pentavalent atom and these impurities will create  n-type semiconductor because of the excess electrons brought about by the phosphorous.

what happens when germanium doped with indium

indium is a trivalent atom , the number of electrons in the outermost electron shell is less than half of the required number for stability. while semiconductor with valence number of electrons half the required number , therefore when silicon is doped with a trivalent atom like indium it “ create more emptiness”  in the silicon and consequently holes are created. therefore when silicon is doped with indium a p-type semiconductor is created.