1

GATE ECE 2005

MCQ (Single Correct Answer)

+2

-0.6

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 conductivity of the sample A to B is2

GATE ECE 2003

MCQ (Single Correct Answer)

+2

-0.6

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 supplied to keep this concentration gradient constant with time.If electronic charge is $$1.6\times10^{-19}\;coulomb$$ and the diffusion constant $$D_n=3\;cm^2/s$$, the current density in the silicon, if no electric field is present is3

GATE ECE 2003

MCQ (Single Correct Answer)

+2

-0.6

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 an electron is 1.6×10^{-19}coulomb, then the resistance of the bar is4

GATE ECE 1992

MCQ (Single Correct Answer)

+2

-0.6

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 id $$\triangle n=10^{15}/cm^3$$ and if $$\tau_p=10\;\mu\;sec$$ [minority carrier life time] the generation rate due to
irradiation

Questions Asked from Semiconductor Physics (Marks 2)

Number in Brackets after Paper Indicates No. of Questions

GATE ECE Subjects

Signals and Systems

Representation of Continuous Time Signal Fourier Series Discrete Time Signal Fourier Series Fourier Transform Discrete Time Signal Z Transform Continuous Time Linear Invariant System Transmission of Signal Through Continuous Time LTI Systems Discrete Time Linear Time Invariant Systems Sampling Continuous Time Signal Laplace Transform Discrete Fourier Transform and Fast Fourier Transform Transmission of Signal Through Discrete Time Lti Systems Miscellaneous Fourier Transform

Network Theory

Control Systems

Digital Circuits

General Aptitude

Electronic Devices and VLSI

Analog Circuits

Engineering Mathematics

Microprocessors

Communications

Electromagnetics