Question

question 1 of 20 :
select the best answer for the question.

1. combining which of the following substances with germanium will cause the germanium to emit free electrons?

a. gallium
b. aluminum
c. indium
d. bismuth
mark for review (will be highlighted on the review page)

Explanation:

To determine which substance causes germanium to emit free electrons, we analyze the doping of semiconductors. Germanium is a semiconductor. Doping with a pentavalent (5 - valence - electron) element creates an n - type semiconductor (with free electrons). Bismuth (Bi) is pentavalent (group 15 element, has 5 valence electrons), while gallium, aluminum, and indium are trivalent (group 13, 3 valence electrons) and form p - type semiconductors (with holes, not free electrons as the majority carrier). So combining germanium with bismuth (a pentavalent dopant) will introduce free electrons.

Answer:

D. Bismuth