# EC 203 SOLID STATE DEVICES KTU MODAL QUESTIONS FOR SECOND YEAR S3

## EC 203 SOLID STATE DEVICES KTU MODAL QUESTIONS FOR SECOND YEAR S3

## APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

**SOLID STATE DEVICES**

**QUESTION PAPERS**

__PART A__

__(Answer All Questions)__

1. Derive an expression for the electron current in the n-type material of a forward biased p-n junction?

2. Define diffusion length of a hole? Mention the relation between carrier life time and diffusion length of hole?

3. Define luminescence? Mention different types of luminescence?

4. For a P+N junction diode, which region is heavily doped? Also prove with suitable equations, which region among P side depletion region or N side depletion will be greater?

5. Draw the energy band diagrams for a PN junction in a) equilibrium b) Forward biased c) Reverse biased cases?

__PART B__

__(Answer Any Two Questions)__

6. Derive the continuity equation?

7. Explain the quasi Fermi level with suitable equations and figures?

8. Derive the diode equation?

9. An abrupt Si p-n junction has Na=10^18 cm^-3 on one side and Nd=5*10^15 cm^-3 on the other side.

The junction has a circular cross section with diameter of 10μm.

Calculate contact potential, Xno, Xpo, depletionregion

width(W), Q+ and €o(electric field)? Given Ɛr=11.8, Ɛ0=8.854*10^-14.

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