GATE Electronics & Communication

The electron mobility $\mu_n$ in a non-degenerate germanium semiconductor at 300 K is $0.38 \mathrm{~m}^2 / \mathrm{Vs}$. The electron diffusivity $D_n$ at 300 K (in $\mathrm{cm}^2...

The intrinsic carrier concentration of a semiconductor is $2.5 \times 10^{16} / \mathrm{m}^3$ at 300 K . If the electron and hole mobilities are $0.15 \mathrm{~m}^2 / \mathrm{Vs}$...

An ideal p-n junction germanium diode has a reverse saturation current of $10 \mu \mathrm{~A}$ at 300 K . The voltage (in Volts, rounded off to two decimal places) to be applied ac...

Which of the following can be used as an n-type dopant for silicon? Select the correct option(s).

For non-degenerately doped n-type silicon, which one of the following plots represents the temperature ($T$) dependence of free electron concentration ($n$)?

Consider a MOS capacitor made with p-type silicon. It has an oxide thickness of 100 nm, a fixed positive oxide charge of $10^{-8}$ C/cm 2 at the oxide-silicon interface, and a meta...

A non-degenerate n-type semiconductor has 5 % neutral dopant atoms. Its Fermi level is located at 0.25 eV below the conduction band ($E_C$) and the donor energy level ($E_D$) has a...

The photocurrent of a PN junction diode solar cell is 1 mA. The voltage corresponding to its maximum power point is 0.3 V. If the thermal voltage is 30 mV, the reverse saturation c...

In a semiconductor, if the Fermi energy level lies in the conduction band, then the semiconductor is known as

For an intrinsic semiconductor at temperature $$T=0K$$, which of the following statement is true?

For a MOS capacitor, $$\mathrm{V_{fb}}$$ and $$\mathrm{V_{t}}$$ are the flat-band voltage and the threshold voltage, respectively. The variation of the depletion width ($$\mathrm{W...

In an extrinsic semiconductor, the hole concentration is given to be 1.5$$n_i$$ where $$n_i$$ is the intrinsic carrier concentration of 1 $$\times$$ 10$$^{10}$$ $$cm^{-3}$$. The ra...

In a semiconductor device, the Fermi-energy level is 0.35 eV above the valence band energy. The effective density of states in the valence band at T = 300 K is 1 $$\times$$ 10$$^{1...

Consider a long rectangular bar of direct bandgap p-type semiconductor. The equilibrium hole density is 10 17 cm $$-$$3 and the intrinsic carrier concentration is 10 10 cm $$-$$3 ....

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 bottom of the conduction ban...

Select the CORRECT statements regarding semiconductor devices

A bar of silicon is doped with boron concentration of $10^{16} \mathrm{cm}^{-3}$ and assumed to be fully ionized. It is exposed to light such that electron-hole pairs are generated...

Consider the recombination process via bulk traps in a forward biased $p n$ homojunction diode. The maximum recombination rate is $U_{\max }$. If the electron and the hole capture...

A single crystal intrinsic semiconductor is at a temperature of 300 K with effective density of states for holes twice that of electrons. The thermal voltage is 26 mV . The intrins...

A $p n$ junction solar cell of area $1.0 \mathrm{~cm}^2$, illuminated uniformly with $100 \mathrm{mWcm}^{-2}$; has the following parameter : Efficiency $=15 \%$, open circuit volta...

A bar of Gallium Arsenide (GaAs) is doped with Silicon such that the Silicon atoms occupy Gallium and Arsenic sites in the GaAs crystal. Which one of the following statement is tru...

For a particular intensity of incident light on a silicon pn junction solar cell, the photocurrent density (J L ) is 2.5 mA/cm 2 and the open-circuit voltage (V$$_{oc}$$) is 0.451...

An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base-collector junction is increased, then

An n-channel enhancement mode MOSFET is biased at V GS > V TH and V DS > (V GS - V TH ), where V GS is the gate-to-source voltage, V DS is the drain-to-source voltage and V TH is t...

Consider an n-channel MOSFET having width W, length L, electron mobility in the channel $$\mu_n$$ and oxide capacitance per unit area $$C_{ox}$$. If gate-to-source voltage V GS =0....

Two n-channel MOSFETs, T1 and T2, are identical in all respects except that the width of T2 is double of T1. Both the transistor are biased in the saturation region of operation, b...

A MOS capacitor is fabricated on p-type Si (silicon) where the metal work function is 4.1 eV and electron affinity of Si is 4.0 eV, E c - E F = 0.9 eV; where E c and E F are conduc...

The Ebers-Moll model of a BJT is valid

Consider the following statements for a metal oxide semiconductor field effect transistor (MOSFET): P: As channel length reduces, OFF-state current increases. Q:As channel length r...

A long-channel NMOS transistor is biased in the linear region with V DS = 50 mV and is used as a resistance. Which one of the following statements is NOT correct?

A voltage V G is applied across a MOS capacitor with metal gate and p-type silicon substrate at T=300 K. The inversion carrier density (in number of carriers per unit area) for V G...

Consider a long-channel NMOS transistor with source and body connected together. Assume that the electron mobility is independent of V GS and V DS . Given, g m = 0.5$$\mu {\rm A}/V...

Consider an n-channel metal oxide semiconductor field effect transistor (MOSFET) with a gate-to-source voltage of 1.8 V. Assume that $${W \over L} = 4,{\mu _{\rm N}}{C_{ox}} = 70 \...

A silicon sample is uniformly doped with donor type impurities with a concentration of $$10^{16}/cm^3$$.The electron and hole mobilities in the sample are $$1200\;cm^2/V-s$$ and $$...

An n–type silicon sample is uniformly illuminated with light which generates 10 20 electron hole pairs per cm 3 per second. The minority carrier lifetime in the sample is 1 $$\math...

A region of negative differential resistance is observed in the current voltage characteristics of a silicon PN junction if

The built-in potential of an abrupt p-n junction is 0.75V. If its junction capacitance (C J ) at a reverse bias (V R ) of 1.25V is 5pF, the value of C J (in pF) when V R = 7.25V is...

In the circuit shown in the figure, the BJT has a current gain (β) of 50. For an emitter-base voltage V EB = 600 mV, the emitter-collector voltage V EC (in Volts) is ______.

If the base width in a bipolar junction transistor is doubled, which one of the following statements will be TRUE?

An npn BJT having reverse saturation current $$I_s\;=\;10^{-15}\;A$$ is biased in the forward active region with V BE = 700 mV. The thermal voltage (V T ) is 25 mV and the current...

Which one of the following processes is preferred to from the gate dielectric (SiO 2 ) of MOSFETs?

In a MOS capacitor with an oxide layer thickness of 10 nm, the maximum depletion layer thickness is 100 nm. The permittivities of the semiconductor and the oxide layer are $${\vare...

A MOSFET in saturation has a drain current of 1 mA for V DS =0.5V. If the channel length modulation coefficient is 0.05 V -1 , the output resistance (in k$$\Omega $$) of the MOSFET...

The current in an enhancement mode NMOS transistor biased in saturation mode was measured to be 1 mA at a drain-source voltage of 5 V. When the drain-source voltage was increased t...

A thin P-type silicon sample is uniformly illuminated with light which generates excess carriers. The recombination rate is directly proportional to

At T = 300 K, the hole mobility of a semiconductor $$\mu_p\;=500\;cm^2/V-s$$ and $$\frac{kT}q\;=\;26\;mV$$.The hole diffusion constant D p in cm 2 /s is__________.

The cut-off wavelength (in µm) of light that can be used for intrinsic excitation of a semiconductor material of bandgap E g = 1.1 eV is ________.

Assume electronic charge q = 1.6×10 -19 C, kT/q = 25 mV and electron mobility μ n = 1000 cm 2 /V-s. If the concentration gradient of electrons injected into a P-type silicon sample...

Consider a silicon sample doped with N D = 1×10 15 /cm 3 donor atoms. Assume that the intrinsic carrier concentration n i = 1.5×10 10 /cm 3 . If the sample is additionally doped wi...

When the optical power incident on a photodiode is 10μW and the responsivity is 0.8 A/W, the photocurrent generated (in μA) is ________.

An increase in the base recombination of a BJT will increase

Consider two BJT's biased at the same collector current with area A 1 = 0.2 μm × 0.2 μm and A 2 = 300 μm × 300 μm. Assuming that all other device parameters are identical, kT/q = 2...

If fixed positive charges are present in the gate oxide of an n-channel enhancement type MOSFET, it will lead to

In CMOS technology, shallow P-well or N-well regions can be formed using

In MOSFET fabrication, the channel length is defined during the process of

An ideal MOS capacitor has boron doping concentration of 10 15 cm -3 in the substrate. When a gate voltage is applied, a depletion region of width 0.5 $$\mu m$$ is formed with a su...

A depletion type N -channel MOSFET is biased in its linear region for use as a voltage controlled resistor. Assume threshold voltage V TH = -0.5 V, V GS = 2.0 V, V DS = 5 V, W/L=10...

The slope of the I D vs. V GS curve of an n-channel MOSFET in linear region is 10 -3 $${\Omega ^{ - 1}}$$ at V DS = 0.1V. For the same device, neglecting channel length modulation,...

In a forward biased P-N junction diode, the sequence of events that best describes the mechanism of current flow is

In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces

In a MOSFET operating in the saturation region, the channel length modulation effect causes

The source of a silicon (n i = 10 10 per cm 3 ) n - channel MOS transistor has an aewa of 1 sq $$\mu m$$ and a depth of 1 $$\mu m$$ . If the dopant density in the source is 10 19 /...

Drift current in the semiconductors depends upon

For a BJT the common base current gain $$\alpha$$ = 0.98 and the collector base junction reverse bias saturation current I CO = 0.6μA. This BJT is connected in the common emitter m...

In a uniformly doped BJT, assume that N E , N B and N C are the emitter, base and collector dopings in atoms/cm 3 , respectively. If the emitter injection efficiency of the BJT is...

Which of the following is true?

Which of the following is NOT associated with a P-N junction?

A silicon wafer has 100 mm of oxide on it and is inserted in a furnace at a temperature above 1000ºC for further oxidation in dry oxygen. The oxidation rate

The measured transconductance g m of an NMOS transistor operating in the linear region is plotted against the gate voltage V G at constant drain voltage V D . Which of the followin...

In a p + n junction diode under reverse bias, the magnitude of electric field is maximum at

A P + -N junction has a built-in potential of 0.8 V. The depletion layer width at a reverse bias of 1.2V is 2 µm. For a reverse bias of 7.2 V, the depletion layer width will be:

The DC current gain ($$\beta$$) of a BJT is 50. Assuming that the emitter injection efficiency is 0.995, the base transport factor is:

Under low level injection assumption, the injected minority carrier current for an extrinsic semiconductor is essentially the

The concentration of minority carriers in an extrinsic semiconductor under equilibrium is:

An n-channel depletion MOSFET has following two points on its I D − V GS curve: (i) V GS = 0 at I D = 12 mA and (ii) V GS = - 6 Volts at I D = 0 Which of the following Q-points wil...

The primary reason for the widespread use of Silicon in semiconductor device technology is

A Silicon PN junction at a temperature of 20°C has a reverse saturation current of 10 pico-Amperes (pA). The reverse saturation current at 40°C for the same bias is approximately

The band gap of Silicon at room temperature is:

A silicon sample 'A' is doped with 10 18 atoms/cm 3 of Boron. Another sample 'B' of identical dimensions is doped with 10 18 atoms/cm 3 of Phosphorus. The ratio of electron to hole...

A Silicon PN junction diode under reverse bias has depletion region of width 10 µm. The relative permittivity of Silicon, ɛ r = 11.7 and the permittivity of free space ɛ 0 = 8.854...