The valence of an impurity added to germanium crystal in order to convert it into a P-type semi conductor is
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NEET Practice Questions (MCQs) with Answers & Solutions
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In a semiconductor, the concentration of electrons is and that of the holes is . The semiconductor is
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Explanation
(b) Since ; the semiconductor is N-type.
The valency of the impurity atom that is to be added to germanium crystal so as to make it a N-type semiconductor, is
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Explanation
To make germanium a N-type semiconductor, we need to introduce a pentavalent impurity atom, such as antimony (Sb), arsenic (As), or phosphorus (P). These impurity atoms have five valence electrons, one more than germanium's four. This extra electron is weakly bound and can move freely, contributing to electrical conductivity.
Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity
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Explanation
(b) Impurity increases the conductivity.
A piece of copper and the other of germanium are cooled from the room temperature to 80 K, then which of the following would be a correct statement
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Explanation
(d) Resistance of conductors (Cu) decreases with decrease in temperature while that of semi-conductors (Ge) increases with decrease in temperature.
To obtain P-type Si semiconductor, we need to dope pure Si with
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Explanation
(a) Aluminum is trivalent impurity
Electrical conductivity of a semiconductor
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Explanation
(b) With temperature rise conductivity of semiconductors increases.
When a semiconductor is heated, its resistance
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Explanation
(a) With temperature rise conductivity of semiconductors increases
In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of
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Explanation
(d) In insulators, the forbidden energy gap is largest and it is of the order of 15 eV.
A N-type semiconductor is
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Explanation
(c) N-type semiconductors are neutral because neutral atoms are added during doping.
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