Semiconductor Electronics: Materials, Devices and Simple Circuits
54 Board Physics previous year questions on Semiconductor Electronics: Materials, Devices and Simple Circuits — options free on every question; 5 include the answer & explanation free, the rest unlock with PYQ Pass.
When a p-n junction diode is forward biased
the barrier height and the depletion layer width both decrease.
barrier height and the depletion layer width both decrease. When p-n junction is forward biased: • The barrier potential decreases. • The depletion layer width decreases due to carrier injection.
Si is doped with a pentavalent element. The energy required to set the additional electron free is about :
0.05 eV
Identify that Si doped with a pentavalent element introduces extra electrons, and the energy required to free these electrons is very low.
Final Answer:(B) 0.05 eV
When a p-n junction diode is subjected to reverse biasing :
the barrier height increases and the depletion region widens.
When a p-n junction diode is reverse biased, a negative voltage is applied to the p-side and a positive voltage to the n-side, causing the depletion region to widen and the barrier potential to increase. This creates a high resistance that prevents the flow of majority carriers, so only a very small current (reverse saturation current) due to minority carriers flows, making the diode act as an open switch.
Ge is doped with As. Due to doping,
the number of conduction electrons increases.
When germanium (Ge), a group-IV element, is doped with arsenic (As), a group-V element, it creates an n-type semiconductor. Arsenic contributes extra electrons (conduction electrons) to the material because it has five valence electrons compared to four in germanium. These extra electrons become free to conduct electricity, thus increasing the number of conduction electrons. Thus, the effect of doping Ge with As is :
the number of conduction electrons increases.
Ge is doped with As. Due to doping,
the number of conduction electrons increases.
Due to doping, the number of conduction electrons increases.
When a p-n junction diode is subjected to reverse biasing :
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When a p-n junction diode is subjected to reverse biasing :
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A pure Si crystal having \(5\times {10}^{28}\) atoms \({\mathrm{m}}^{-3}\) is dopped with 1 ppm concentration of antimony. If the concentration of holes in the doped crystal is found to be \(4.5\times {10}^{9}{\mathrm{m}}^{-3}\), the concentration (in \({\mathrm{m}}^{-3}\)) of intrinsic charge carriers in Si crystal is about
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Si is doped with a pentavalent element. The energy required to set the additional electron free is about :
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Ge is doped with As. Due to doping,
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Ge is doped with As. Due to doping,
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An n-type semiconducting Si is obtained by doping intrinsic Si with :
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An n-type semiconducting Si is obtained by doping intrinsic Si with :
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When a p-n junction diode is forward biased
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Which of the following statements is not true for a p-n junction diode under reverse bias ?
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Ge is doped with As. Due to doping,
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When a p-n junction diode is forward biased
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Which of the following statements is not true for a p-n junction diode under reverse bias ?
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Si is doped with a pentavalent element. The energy required to set the additional electron free is about :
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When a p-n junction diode is forward biased
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When a p-n junction diode is subjected to reverse biasing :
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Ge is doped with As. Due to doping,
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Ge is doped with As. Due to doping,
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When a p-n junction diode is subjected to reverse biasing :
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When a p-n junction diode is forward biased
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An AND gate is followed by a NOT gate. If the inputs to the AND gate are A and B, determine the final output of the circuit in terms of A and B.
(Shift - II Memory based)
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Ge is doped with As. Due to doping,
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A pure Si crystal having \(5\times {10}^{28}\) atoms \({\mathrm{m}}^{-3}\) is dopped with 1 ppm concentration of antimony. If the concentration of holes in the doped crystal is found to be \(4.5\times {10}^{9}{\mathrm{m}}^{-3}\), the concentration (in \({\mathrm{m}}^{-3}\)) of intrinsic charge carriers in Si crystal is about
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A pure Si crystal having \(5\times {10}^{28}\) atoms \({\mathrm{m}}^{-3}\) is dopped with 1 ppm concentration of antimony. If the concentration of holes in the doped crystal is found to be \(4.5\times {10}^{9}{\mathrm{m}}^{-3}\), the concentration (in \({\mathrm{m}}^{-3}\)) of intrinsic charge carriers in Si crystal is about
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Consider the following statements:
A. The junction area of solar cell is made very narrow compared to a photo diode.
B. Solar cells are not connected with any external bias.
C. LED is made of lightly doped p-n junction.
D. Increase of forward current results in continuous increase of LED light intensity.
E. LEDs have to be connected in forward bias for emission of light.
Choose the correct answer from the options given below:
[JEE Main 2025, 24 Jan (Shift 1)]
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When a p-n junction diode is forward biased
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When a p-n junction diode is forward biased
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The acceptor level of a p-type semiconductor is \(6 eV\). The maximum wavelength of light which can create a hole would be : Given \(hc =1242 eV nm\).
[JEE Main 2024, 6 Apr (Shift 2)]
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Which of the following statements is not true for a p-n junction diode under reverse bias ?
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Si is doped with a pentavalent element. The energy required to set the additional electron free is about :
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Ge is doped with As. Due to doping,
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An n-type semiconducting Si is obtained by doping intrinsic Si with :
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When a p-n junction diode is subjected to reverse biasing :
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In an extrinsic semiconductor, the number density of holes is \(4 \times 10^{20} m ^{-3}\). If the number density of intrinsic carriers is \(1.2 \times 10^{15} m ^{-3}\), the number density of electrons in it is
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Statement-I: When a \(Si\) sample is doped with Boron, it becomes P type and when doped by Arsenic it becomes N-type semi conductor such that P-type has excess of holes and N-type has excess of electrons.
Statement-II: When such P-type and N-type semiconductors, are fused to make a junction, a current will automatically flow which can be detected with an externally connected ammeter.
In light of the above statements, choose the most appropriate answer from the options given below.
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The increase in the width of the depletion region in a \( p \) - \( n \) junction diode is
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When an intrinsic semiconductor is doped with a small amount of trivalent impurity, then :
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At a certain temperature in an intrinsic semiconductor, the electrons and holes concentration is \(1.5 \times 10^{16} m ^{-3}\). When it is doped with a trivalent dopant, hole concentration increases to \(4.5 \times 10^{22} m ^{-3}\). In the doped semiconductor, the concentration of electrons \(\left( n _{ e }\right)\) will be :
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For questions , two statements are given - one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
Assertion (A) : The temperature coefficient of resistance is positive for metals and negative for p-type semiconductors.
Reason (R) : The charge carriers in metals are negatively charged, whereas the majority charge carriers in p-type semiconductors are positively charged.
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Assertion (A): In ' \(n\) ' type semiconductor, number density of electrons is greater than the number density of holes but the crystal maintains an overall charge neutrality.
Reason (R): The charge of electrons donated by donor atoms is just equal and opposite to that of the ionised donor.
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Assertion (A) : The resistance of an intrinsic semiconductor decreases with increase in its temperature.
Reason (R) : The number of conduction electrons as well as hole increase in an intrinsic semiconductor with rise in its temperature.
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Assertion (A) : We cannot form a p-n junction diode by taking a slab of a p-type semiconductor and physically joining it to another slab of a n-type semiconductor.
Reason (R) : In a p-type semiconductor \({\eta }_{\mathrm{e}}≫{\eta }_{\mathrm{h}}\) while in a n-type semiconductor \({\eta }_{\mathrm{h}}≫{\eta }_{\mathrm{e}}\).
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In the energy-band diagram of n-type Si semiconductor, the gap between the bottom of the conduction band \(E_C\) and the donor energy level \(E_D\) is of the order of:
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The formation of depletion region in a p-n junction diode is due to
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If a p-n junction diode is reverse biased,
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During the formation of a \(p-n\) junction :
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Two statements are given - one labelled Assertion (A) and the other labelled Reason \((R)\). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
Assertion (A) : In a semiconductor, the electrons in the conduction band have lesser energy than those in the valence band.
Reason ( \(R\) ) : Donor energy level is just above the valence band in a semiconductor.
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Assertion (A): Silicon is preferred over Germanium for making semiconductor devices.
Reason \((R)\) : Silicon can be used at a higher temperature as compared to Germanium.
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Which of the following gate is called universal gate ?
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