Semi conductor devices practice · Mixed difficulty

Avalanche breakdown of p-n junction diode is due to

In a $P$-type semiconductor

Which of the following statements are CORRECT?

Statement I: When a battery is connected across the junction diode with its negative terminal connected to the p-side and the positive terminal connected to the $\mathrm{n}$-side, the diode is said to be forward biased.

Statement II: In forward bias condition, if the bias voltage is greater than the barrier potential, the majority carries move towards the junction and cross it.

Statement III: In reverse biasing of a diode, the majority carriers are pulled away from the junction, making the depletion layer wider.

Assertion: Positive feedback is essential for converting a transistor into an oscillator.
Reason: Positive feedback works between cut-off and saturation region.

The saturation current in a diode valve is governed by

The conductivity of an intrinsic semiconductor depends on temperature as $\sigma=\sigma_0 e^{-\Delta E / 2 k T}$, where $\sigma_0$ is a constant. Find the temperature at which the conductivity of an intrinsic germanium semiconductor will be double of its value at $T=300 \mathrm{~K}$. Assume that the gap for germanium is $0.650 \mathrm{~eV}$ and remains constant as the temperature is increased.

In semiconductor diode, the barrier potential offers opposition to flow of

Assertion : When the temperature of a semiconductor is increased, then its resistance decreases

Reason : The energy gap between conduction band and valence band is very small

Assertion: A P-N photodiode is made from a semiconductor for which $\mathrm{Eg}=2.8 \mathrm{eV}$. This photodiode will not detect the wavelength of $6000 \mathrm{~nm}$.

Reason: A PN photodiode detects wavelength I if $\frac{h c}{\lambda} > E_g$

In a cubic unit cell of bcc structure, the lattice points ($ie$, number of atoms) are

In an unbiased p-n junction, holes diffuse from the p-region to n-region because of

Consider the following statements (A) and (B) and identify the correct answer.
(A) Zener diode can be used as voltage regulator.
(B) In unbiased p-n junction, at thermal equilibrium, drift current is equal to diffusion current.

The energy band gap is maximum in

Assertion : Generally semiconductors do not obey Ohm’ law.

Reason : Electric current is determined by the rate of flow of charge carriers.

Why do we prefer indirectly heated cathode to the directly heated cathode?

In $P$-type semiconductor the majority and minority charge carriers are respectively

Radiowaves of constant amplitude can be generated with

A common emitter amplifier has a voltage gain of 50, an input impedance of 100 $\Omega$ and an output impedance of 200$\Omega$ . The power gain of the amplifier is

Calculate the current amplification factor $\beta$ (beta) when change in collector current is 1 mA and change in base current is $20\,\mu A.$

The coordination number of hexagonal close packing (hcp) is

The majority charge carriers in $P$-type semiconductor are

The typical ionisation energy of a donar in silicon is

The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon starts energy absorption, will be($h = 6.62 \times {10^{ - 34}}\mathrm{\;Js};\mathrm{c} = 3 \times {10^8}\mathrm{m}{\mathrm{s}^{ - 1}}$)

The output from a NAND gate is 0 when the inputs A, B and C are such that.

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Photodiodes are preferably operated in reverse bias condition for light intensity measurement.

Reason R: The current in the forward bias is more than the current in the reverse bias for a $p-n$ junction diode.

In the light of the above statements, choose the correct answer from the options given below:

In a fcc lattice structure, what is the effective number of atoms?

During regulation action of a Zener diode correct statement is :-

(a) the current and voltage across the Zener remains fixed.

(b) the current through the series resistance $\left(\mathrm{R}_{\mathrm{S}}\right)$ changes.

(c) the Zener resistance is constant.

(d) the resistance offered by the Zener diode changes.

The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be

The forbidden energy band gap in conductors, semiconductors and insulators are $E{G_1},\;E{G_2}$ and $E{G_3}$ respectively. The relation them is

A transistor oscillator is

(i) An amplifier with positive feedback

(ii) An amplifier with reduced gain

(iii) The one in which DC supply energy is converted into AC output energy. Then