211. Germanium may be made p-type by adding acceptor impurities
A. during the normal-freezing process.
B. during the zone-refining process.
C. during the crystal-pulling process.
D. before purification begins.

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212. A seed crystal is
A. a single crystal containing the donor or acceptor impurities.
B. a crystal in the liquid state.
C. a single crystal with a particular orientation.
D. a crystal formed by expitaxial growth.

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213. An inert gas is pumped into the quartz tube during zone refining to
A. add acceptor impurities to the melt.
B. absorb impurities from the melt.
C. make melting occur at a lower temperature.
D. prevent the melt from absorbing impurities from the air.

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214. Epitaxial growth is best suited for
A. growing single crystals several inches long.
B. obtaining polycrystalline germanium.
C. obtaining polycrystalline silicon.
D. growing very thin single crystals on a substrate.

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215. Epitaxial growth is obtained by
A. freezing the melted semiconductor metarial.
B. melting and then refreezing the semiconductor material.
C. depositing the semiconductor material on to a heated surface.
D. pulling a solid from the liquid.

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216. An epitaxial germanium film may be doped by
A. using hydrogen gas as a carrier.
B. using chlorine to form the vapor compound.
C. introducing the doping impurity as a vapor along with the germanium compound vapor.
D. adding the doping impurity to the melt.

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217.  Resistivity measurements are often used to determine
A. the lifetime of polycrystalline materials.
B. carrier concentration in intrinsic semiconductors.
C. carrier concentration in extrinsic semiconductors
D. carrier mobility

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