List of top Electronic Devices Questions

The intrinsic carrier concentration of a semiconductor is \( 2.5 \times 10^{16} \, /m^3 \) at 300 K. If the electron and hole mobilities are \( 0.15 \, {m}^2/{Vs} \) and \( 0.05 \, {m}^2/{Vs} \), respectively, then the intrinsic resistivity of the semiconductor (in \( k\Omega \cdot m \)) at 300 K is _________. (Charge of an electron \( e = 1.6 \times 10^{-19} \, C \))

Match List I with List II

List I (Technology)		List II (Range)
A	Bluetooth	I	10 cm to 200 m
B	LoRa	II	10 m to 20 m
C	RFID	III	1 m to 100 m
D	ZigBee	IV	2 km to 15 km

Choose the correct answer from the options given below:

Which statements are true?
A. Electric field,  $\xi (x)$, in a semiconductor is directly proportional to the slope of the intrinsic Fermi level. 
B. Continuity equation is a mathematical representation of Fermi-Dirac distribution function. 
C. Depletion width in a P-N junction is equal to its Debye length. 
D. Diffusion current density for holes is equal to $[-qD_{\rho}, \frac{dp(x)}{d(x)} ]$
Choose the correct answer from the options given below.

Match List I with List II

List I  (Circuits)		List II (Components)
A	In an ideal op-amp integrator	I	A parallel RLC network in the feedback path
B	In an ideal op-amp differentiator	II	An E-MOSFET is used that work as switch
C	In an op-amp sample and hold circuit	III	A capacitor is in feedback path
D	In an op-amp peaking amplifier	IV	A resistor is in feedback path

Choose the correct answer from the options given below:

Which statement(s) is/are true?
A. The drain current in an enhancement-type MOSFET is inversely proportional to the relative permittivity of the gate oxide. 
B. The threshold voltage in an MOS capacitor does not depend on the gate oxide thickness. 
C. The drain current in an enhancement-type MOSFET is directly proportional to the relative permittivity of the gate oxide. 
D. The threshold voltage in an MOS capacitor depends on the gate oxide thickness.
Choose the correct answer from the options given below.

Given below are two statements:
Statement-I: Velocity saturation in silicon occurs at high electric fields. 
Statement-II : Mobilities due to two scattering mechanisms (μ and μ2) add up inversely as $ \frac1{μ}  =\frac1{μ_1} +\frac1{μ_2} $ 
In the light of the above statements, choose the correct answer from the options given below.

Given below are two statements :
Statement-I: The $r_e$ model has advantage that the parameters are defined by the actual operating conditions. 
Statement-II: The parameters of the hybrid equivalent circuit are defined in general terms for any operating conditions. 
In the light of the above statements, choose the correct answer from the options given below.

An evanescent mode occurs when

A polar diagram, which represents a lag network, is

In a silicon sample doped with N-type impurities, the Fermi level $(E_F)$ is situated 0.35 eV away from the intrinsic Fermi level $(E_i)$. If the energy bandgap $(E_g)$ of silicon at 300 K is considered to be 1.10 eV, what is the separation between the Fermi level $(E_F)$ and the valence band edge $(E_v)$?

In which quadrant of the current-voltage characteristic does a solar cell operate?

Maximum electric field in a P-N junction in equilibrium is located

The conduction band edge, $E_c$, in a semiconductor represents

The value of solar constant is.

The relationship among the emitter capacitance (Ce), the diffusion capacitance (C_De) and the transition capacitance (C_Te) cs given by:

The statements which are correct with referred to solar cell are:
A. The short circuit current of a solar cell changes logarithmically with radiation
B. At maximum power point of the solar cell the product of voltage and current are maximum
C. Energy pay back period of a single crystal silicone cell is 10 to 20 years
D. At maximum power point of the solar cell both voltage and current are maximum
E. Energy pay back period of a single crystal silicon cell is 1 to 3 years
Choose the correct answer from the options given below:

A p-type semiconductor in steady state has excess minority carriers zero at $x=\pm 2L_n$, with $L_n = 10^{-4}$ cm. Electron charge $q = -1.6\times 10^{-19}$ C. The recombination rate profile is \[ R = 10^{20} \exp\left(-\frac{|x|}{L_n}\right)\ \text{cm}^{-3}\text{s}^{-1}. \] The magnitude of electron current density at $x=+2L_n$ is __________ mA/cm$^2$ (rounded to two decimals).

Select the CORRECT statement(s) regarding semiconductor devices.

Consider an ideal long channel nMOSFET (enhancement-mode) with gate length 10 $\mu$m and width 100 $\mu$m. The product of electron mobility ($\mu_n$) and oxide capacitance per unit area ($C_{OX}$) is $\mu_n C_{OX} = 1\ \text{mA/V}^2$. The threshold voltage of the transistor is 1 V. For a gate-to-source voltage $V_{GS} = [2 - \sin(2t)]$ V and drain-to-source voltage $V_{DS} = 1$ V (substrate connected to source), the maximum value of the drain-to-source current is ________________.

An ideal MOS capacitor (p-type semiconductor) is under strong inversion with $V_G = 2$ V. The inversion charge density is $Q_{IN} = 2.2\ \mu\text{C/cm}^2$. Assume oxide capacitance per unit area $C_{ox} = 1.7\ \mu\text{F/cm}^2$. For $V_G = 4$ V, the value of $Q_{IN}$ is ____________ $\mu$C/cm$^2$ (rounded to one decimal place).

Consider a long rectangular bar of direct bandgap $p$-type semiconductor. The equilibrium hole density is $10^{17}\,\text{cm}^{-3}$ and the intrinsic carrier concentration is $10^{10}\,\text{cm}^{-3}$. Electron and hole diffusion lengths are $2\,\mu$m and $1\,\mu$m, respectively. The left side of the bar ($x=0$) is uniformly illuminated with a laser having photon energy greater than the bandgap of the semiconductor. Excess electron-hole pairs are generated ONLY at $x=0$ because of the laser. The steady state electron density at $x=0$ is $10^{14}\,\text{cm}^{-3}$ due to laser illumination. Under these conditions and ignoring electric field, the closest approximation (among the given options) of the steady state electron density at $x=2\,\mu\text{m}$ is ______________.

In a non-degenerate bulk semiconductor with electron density $n = 10^{16}$ cm$^{-3}$, the value of $(E_C - E_{Fn}) = 200$ meV, where $E_C$ and $E_{Fn}$ denote the conduction band edge and electron Fermi level, respectively. Assume thermal voltage as 26 meV and intrinsic carrier concentration as $10^{10}$ cm$^{-3}$. For $n = 0.5 \times 10^{16}$ cm$^{-3}$, the closest approximation of $(E_C - E_{Fn})$, among the given options, is ________________.