Semiconductors

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 $0.15 \mathrm{~m}^2 / \mathrm{Vs}$ and $0.05 \mathrm{~m}^2 / \mathrm{Vs}$,...

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 $\mathrm{cm}^2 / \mathrm{s}$, rounded off to the neare...

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

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 degeneracy of 2. Assuming the thermal v...

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

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 ratio of electron to hole mobility for equ...

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$$^{19}$$ cm$$^{-3}$$. The thermal equilibriu...

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

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 . Electron and hole diffusion lengthss ar...

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 band energy and electron Fermi level energy...

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 throughout the volume of the bar at the...

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 intrinsic Fermi level is shifted from midbandga...

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 true?

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 $$400\;cm^2/V-s$$ respectively. Assume com...

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 $$\mathrm\mu$$s.In the steady state, the hole c...

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 ________.

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__________.

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

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 with N A = 1×10 18 /cm 3 acceptor atoms, t...

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 is 1×10 21 /cm 4 , the magnitude of ele...

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 /cm 3 , the number of holes in the source...

Drift current in the semiconductors depends upon

Which of the following is true?

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

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

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

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 mobility is 1/3. The ratio of conductiv...

The electron concentration in a sample of uniformly doped n-type silicon at 300 o K varies linearly from $$10^{17}/cm^3$$ at x = 0 to $$6\times10^{16}/cm^3$$ at x = 2 $$\mu m$$. Assume a situation that electrons are supp...

An n-type silicon bar 0.1 cm long and $$100\;\mu m^2$$ in cross-sectional area has a majority carrier concentration of $$5\times10^{20}/m^3$$ and the carrier mobility is $$0.13\;\;m^2/v-s\;$$ at 300 o K. if the charge of...

n-type silicon is obtained by doping silicon with

The intrinsic carrier concentration of silicon sample at 300 o K is $$1.5\times10^{16}/m^3$$. If after doping, the number of majority carriers is $$5\times10^{20}/m^3$$ , minority carrier density is

The band gap of silicon at 300 K is

The units of $$\frac q{KT}$$ are

The probability that an electron in a metal occupies the Fermi-level at any temperature (> 0 K)

In a P-type silicon sample, the hole concentration is $$2.25\times10^{15}/cm^3$$. If the intrinsic carrier concentration is $$1.5\times10^{15}/cm^3$$ , the electron concentration is

The drift velocity of electrons in silicon

A small concentration of minority carries is injected into a homogeneous semiconductor crystal at one point. An electric field of 10 V/cm is applied across the crystal and this moves the minority carriers a distance of 1...

A p-type silicon sample has a higher conductivity compared to an n-type sample having the same dopant concentration.

A semiconductor is irradiated with light such that carriers are uniformly generated throughout its volume. The semiconductor is n-type with $$N_D=10^{19}/cm^3$$. If the excess electron concentration in the steady state i...

A silicon sample is uniformly doped with 10 16 phosphorous atoms/cm 3 and 2 ×10 16 boron atoms/cm 3 . If all the dopants are fully ionized, the material is

In an intrinsic semiconductor the free electron concentration depends on