1

GATE ECE 2015 Set 2

Numerical

+2

-0

A dc voltage of 10V is applied across an n–type silicon bar having a rectangular cross–section
and a length of 1cm as shown in figure. The donor doping concentration N

_{D}and the mobility of electrons $$\mu$$n are $$10^{16}$$ cm^{-3}and 1000 cm^{2}V^{-1}s^{-1}, respectively. The average time (in $$\mu$$s) taken by the electrons to move from one end of the bar to other end is _______________.Your input ____

2

GATE ECE 2014 Set 4

Numerical

+2

-0

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, the approximate number of electrons/cm^{3}in the sample, at T=300 K, will be _________________.Your input ____

3

GATE ECE 2014 Set 4

MCQ (Single Correct Answer)

+2

-0.6

An N-type semiconductor having uniform doping is biased as shown in the figure.

If E_{C} is the lowest energy level of the conduction band, E_{V} is the highest energy level of the
valance band and E_{F} is the Fermi level, which one of the following represents the energy
band diagram for the biased N-type semiconductor?

4

GATE ECE 2014 Set 2

Numerical

+2

-0

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 electron diffusion current density (in A/cm^{2}) is _________.Your input ____

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