Semi conductor devices practice · Mixed difficulty

The relation between $\alpha$ and $\beta$ parameters of current gains for a transistors is given by:

If ${D_e}$ , ${D_b}$ and ${D_c}$ are the doping levels of emitter, base and collector respectively of a transistor, then

Boolean expression for XNOR gate can be written as

Which of the following regions of output characteristic of transistor is used when it is used as amplifier?

Boolean expression for $OR$ gate is

If control grid is made negative, then the plate current will

If $\mathrm{\alpha \; and \; \beta }$ are the current gain in the $CB$ and $CE$ configurations respectively of the transistor circuit, then $\frac{{\mathrm{\beta } - \mathrm{\alpha }}}{{\mathrm{\alpha \beta }}}$ is equal

Identify the system of crystal structure, if $a = b \ne c\;\;\alpha = \beta = 90^\circ$ and $\gamma = 120^\circ$.

In Colpitt oscillator the feedback network consists of

Assertion: An N-type semiconductor has a large number of electrons but still it is electrically neutral.
Reason: An N-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.

A $n-p-n$ transistor can be used as

Mutual conductance of triode is $2\mathrm{\;m}{\mathrm{\Omega }^{ - 1}}$ and the amplification factor is 50. Its anode is connected with a source of 250 V and a resistance of $25\mathrm{\;k\Omega }$. The voltage gain of this amplifier is

A $p - n\;$ junction has acceptor impurity concentration of ${10^{17}}\mathrm{c}{\mathrm{m}^{ - 3}}$ in the $P$ side and donor impurity concentration of ${10^{16}}$ $\mathrm{c}{\mathrm{m}^{ - 3}}$ in the $N$ side. What is the contact potential at the junction? ($kT =$ thermal energy, intrinsic carrier concentration ${n_i} = 1.4 \times {10^{10}}$ $\mathrm{c}{\mathrm{m}^{ - 3}}$ )

In a half wave rectifier output is taken across a $90 \, \mathrm{ohm}$ load resistor. If the resistance of diode in forward biased condition is $10 \, \mathrm{ohm}$, the efficiency of rectification of ac power into dc power is

The relation between $\alpha$ and $\beta$ parameters of a transistor is given by

The temperature of germanium is decreased from room temperature to 100 K, the resistance of germanium

Given below are three statements.

A. At absolute zero, Si acts as a perfect insulator.

B. When p-n junction diode is forward biased, both the thickness of depletion region and the barrier height are increased.

C. Order of energy band gap of C, Si and Ge is $(\mathrm{E})_{\mathrm{C}}>(\mathrm{E})_{\mathrm{Si}}>(\mathrm{E})_{\mathrm{Ge}}.$

Choose the correct answer from the options given below.

Thermionic emission from a heated filament varies with its temperature $T$ as

If the ends $p$ and $n$ of $p - n$ diode junction are joined by a wire

If $l_1, l_2, l_3$ are the lengths of the emitter, base and collector of a transistor, then

Calculate the current (in A) produced in a germanium plate of thickness $0.25 \mathrm{~mm}$ and area $1 \mathrm{~cm}^2$ when a potential difference of $1.5 \mathrm{~V}$ is applied across the thickness. The hole density in germanium is $2 \times 10^{19} \mathrm{~m}^{-3}$ and the mobilities of electrons and holes are $350 \mathrm{~cm}^2 \mathrm{~V}^{-1} \mathrm{~s}^{-1}$ and $1200 \mathrm{~cm}^2 V^{-1} \mathrm{~s}^{-1}$ respectively.

Assertion : For forward biasing, positive terminal of external battery is connected to p-type and negative terminal of external battery is connected to n-type semiconductor.

Reason : This would support the tendency of majority charge carriers to cross the junction.

When an impurity is doped into an intrinsic semiconductor, the conductivity of the semiconductor

Of the following which relation is true?

Identical piece of Ge and Cu are taken and cooled,
then:

Which of the following logic gate is an universal gate

The temperature coefficient of resistance of a conductor is

A zener diode has a contact potential of 1 V in the absence of biasing. It undergoes Zener breakdown for an electric field of ${10^6}$ V-${\mathrm{m}^{ - 1}}$ at the depletion region of $p$-$n$ junction. If the width of the depletion region is 2.5 $\mu$m, what should be the reverse biased potential for the Zener breakdown to occur?

The mobility of free electrons is greater than that of free holes because they

In a triclinic crystal system