106. In preparing a semiconductor material for use in semiconductor devices the first step involved is
A. crystal growth
B. chemical purification
C. crystal pulling
D. zone refining

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107.  Final purification of germanium of silicon is generally accompished by
A. chemical purification
B. crystal pulling
C. zone refining
D. epitaxial growth

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108. Purification of silicon is difficult because
A. its melting temperature is high
B. its surface tension is high
C. it does not form a single crystal
D. its resistivity is high

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109.  Seed crystal used in crystal growth is
A. a small crystal formed by epitaxial growth
B. a single crystal with a specific orientation
C. a single crystal containing donor impurity
D. a single crystal containing acceptor impurity

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110. Semiconductor may be made n-type by adding donor impurity
A. during zone refining
B. during chemical purification
C. during crystal pulling
D. before purification process

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111. Epitaxial growth is best suited for growing
A. polycrystalline silicon
B. very thin single crystal layer on a substrate
C. single crystals several inches in size
D. sngle crystals several mm in size

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112. Germanium epitaxial film may be doped by
A. using hydrogen as carrier
B. adding doping impurity in the melt introducing the doping impurity in vapour form along with the germanium compound vapor
C. using chlorine to form the vapour compound
D. All the above

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