Download AKTU B-Tech 6th Sem 2015-2016 EEC 013 Advanced Semiconductor Devices Question Paper

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EEC-013

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(Following Paper ID and Roll No. to be filled in your Answer Books)

Paper ID : 131653

Roll No.

B.TECH.

Theory Examination (Semester-VI) 2015-16

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ADVANCED SEMICONDUCTOR DEVICES

Time : 3 Hours

Max. Marks : 100

Section-A

1. Attempt all parts. All parts carry equal marks. Write answer of each part in short. (2×10=20)

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1. The Si energy gap changes monotonically with temperature. What is the basic concept behind this?
2. Draw the energy level diagram of a PN junction.
3. How a junction barrier is developed across an unbiased junction?
4. Make the energy band diagram of a metal and semiconductor junction at equilibrium. Consider Al metal having a large work function and n-type semiconductor.
5. Why does current saturate in long channel MOSFET when large drain voltage is applied on drain?

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6. A pn junction photodiode is operated under photovoltaic condition similar to solar cell and having the similar I-V Characteristics. under illumination. State three major differences between photodiode and solar cell.
7. What is kinetic energy of a hole at the top of the valence band?
8. Define minority carrier life time.
9. What are the different types of degenerate Semiconductors?
10. What is meant by IMPATT diode?

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Section-B

2. Attempt any five questions from this section. (10×5=50)

1. (i) Explain the recombination of excess carriers in semiconductors. Derive an expression for excess carrier lifetime.
   (ii) Derive an expression for hole and electron diffusion current.
2. Prove that for a linearly graded PN junction the maximum electric field in depletion region is 3/2 times of average electric field.

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3. Derive the current expression for long base ideal diode.
4. Write down the different methods to calculate the barrier height of a Schottky barrier diode.
5. Explain the formation of rectifying M-S contact barrier process using Schottky-Mott theory.
6. Derive an expression for a saturated drain current of a n-channel MESFET.
7. Explain the principle of operation, storage and transfer of charge in basic charge coupled device (CCD).

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8. Derive an expression for power output and efficiency of a MSM BAITT diode.

Section-C

Attempt any two questions from this section. (15×2=30)

3. The donor and acceptor concentration in Si sample is 6×10¹⁵ and 2×10¹⁵ cm^-3 respectively. Determine the position of Fermi

Level with respect to intrinsic energy level Ei at room temperature. Also find out the value and sign of Hall coefficient.

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4. Explain the MESGET operation in case of Depletion mode and enhancement mode device. Draw the I-V characteristic also.

5. A hetero-junction is formed between n-type Ge (with Nd=1.5×10¹⁶ cm^-3) and p-type GaAs (with Na=8.5×10¹⁵ cm^-3).

1. Draw the thermal equilibrium energy band diagram of junction.
2. Calculate the built-in voltage of the junction.

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