What kind of semiconductor--n-type or p-type--does doping germanium with arsenic create?
COLLECT AND ORGANIZE We are asked to determine the type of semiconductor formed when germanium (Ge,group 14) is doped with arsenic (As, group 15).
ANALYZE The fact that As is in group 15 mean that its atoms have one more valence electron that the atoms of Ge.
SOLVE When the dopant has more valence electrons than the host semimetal, the two form an n-type semiconductor.
THINK ABOUT IT Arsenic is a good candidate for making an n-type semiconductor because its atoms are nearly the same size as those of germanium and so fit easily into the structure of solid Ge.
Practice Exercise Gallium arsenide (GaAs) is a semiconductor used in optical scaners in retail stores. GaAs can be made an n-type or a p-tpye semiconductor by replacing some of the As with another element. Which element--Se or Sn--would form an n-tpye semiconductor with GaAs, and which would form a p-type semiconductor?