197. The instrinsic carrier concentration at room temperature is higher in germanium than in silicon because
A. the energy gap in germanium is smaller than the energy gap in silicon.
B. the energy gap in silicon is smaller than the energy gap in germanium.
C. carrier mobilities are higher in germanium than in silicon.
D. carrier mobilities are higher in silicon than in germanium.
198. Most of drift-current flow in intrinsic germanium is due to the freeelectrons because
A. there are more free electrons than holes.
B. a free electron has greater charge than hole.
C. the free electrons are in the valence band.
D. the mobility of the free electrons is greater than the mobility of the holes.
199. Excess minority carriers are the minority carriers that are
A. thermally generated.
C. in excess of the equilibrium number.
D. in excess of the number of majority carriers.
200. Resistivity is a property of semiconductors that depends on the
A. shape of the semiconductor.
B. atomic nature of the semiconductor.
C. shape and the atomic nature of the semiconductor.
D. length of the semiconductor.
201. Diffusion length of carriers depends on the
A. mobility and life time of the carriers.
B. lifetime of the carriers only.
C. mobility of carriers only.
D. shape of the semiconductor.
202. Imperfection in the crystal structure
A. decrease resistivity.
B. decrease mobility.
C. increase mobility.
D. increase conductivity.
203. The first step in preparing semiconductor materials is
A. Crystal growing
B. Chemical purification.
C. Crystal pulling.
D. Zone refining.
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