# RTU Previous Question Papers BE EC 3rd Semester

# Electronic Materials and Processes Feb-2011

**Unit-I**

1. a) Prove the Clausius – Mosotti relation=N(α_{e}+α_{i}) approximate this relation at IR (infra red) region.

b) Explain the interfacial polarization and its dynamic response. Draw its frequency spectra and dipolar relaxation.

**OR**

a) Derive the temperature – independent condition. For a resonant tank circuit.

b) For a solid contains SxlO^{28} atoms/m^{3} with polarizability 2xlQ*^{38} farad m^{2}. Find the strength ratio of internal field to external applied field for corentz distribution.

c) Draw the polarization with applied field for

i) Ferro Electric and

ii) Antiferro Electric Materials.

**Unit-II**

2. a) Draw the susceptibility with temperature for Dia, Para, ferro, ferri and ant ferromagnetic materials.

b) The Magnetic field strength in a piece of copper is 10^{6} ampere nr^{1}. Given that the Magnetic susceptibility of copper is -0.5*10‘^{5}, find the flux density and the Magnetization in the copper.

**OR**

a) Define

i) initial permeability

ii) remenant magnetization

iii) coercive force

iv) saturation magnetization

On BH loop for a soft magnetic material. Compare their values from a Hard magnetic material.

b) Explain the Domain theory, Domain growth under magnetization and domain walls for a ferromagnetic materials.

**Unit-III**

3. a) Write three difference for each

i) Degenerate and Non-degenerate semiconductor material .

ii) GaAs and Si semiconductor.

iii) EGS (Electronic Grade Silicon) and MGS (Mechanical Grade Silicon).

iv) Direct and Indirect Band gap semiconductors.

b) Derive the continuity equation for P-type semiconductor that is illuminated and open-circuit.

**OR**

3. (a) A compound semiconductor is given by A-y then find the

value ofx &y for give the effective Bandgap Eg = 3.8ev. Given that Bandgap

of AlAs —>3.8 ev GaAs—> lAev P -> 4.2 ev.

Also find the corresponding wavelength for which it responds maximum.

b) How control or, depends the purity / defects on

i) temperature gradient

ii) pulling / zone refining speed

in) zone cross section / diameter of the ingot iv) no. of cycles of zone refine in a zone refining process.

**Unit-IV**

4. a) Define

i) Mean free path

ii) Relaxation time

iii) Fermi velocity

iv) Scattering points

v) Drift velocity for electrons

b) Derive the relation and for metals, draw <r(w) with frequency,

**OR**

a) Define the following conduction phenomena

i) Hopping conduction

ii) Diffusion conduction

iii) Drift conduction.

Also state the conditions for which above phenomena applicable.

b) Write four differences between Type I and Type II semiconductor. Write the basis of BCC theory of superconductivity.

**Unit-V**

5. a) Write the name of Mostly used capacitors used for the range (4×2=8)

i) below picofarrad

ii) nano- picofarrad

iii) microfarrad

iv) millifarrad.

Also write their power range and mechanical structures.

b. Calculate the value of resistorsgoldI ‘green Black Blue

N_{d}= 9x 10^{14}/cm^{3}

(cross section) ———– 100 cm

n – type silicon sample having n. = 1.5><10^{,0}/cm^{3}

M^{2} .volt

K = 1400// =300 ^{n}

**OR**

Write short notes on any four:

a) SOI

b) Ferrite/hexaferrite core with silicon doping

c) Laminated transformer core

d) Double layer PCB

e) Variable inductors.