(SEM III) THEORY EXAMINATION 2022-23 ELECTRONIC DEVICES

This question paper evaluates the understanding of semiconductor physics, pn junction behavior, BJT and MOSFET operation, quantum mechanics fundamentals, and carrier transport mechanisms. It is divided into three structured sections:

SECTION A — Short Answer Questions (20 Marks)

This section contains 10 conceptual questions, each carrying 2 marks, designed to test fundamental knowledge of:

Energy band theory and classification of materials                      Carrier transport (drift vs diffusion)

PN junction diode characteristics and depletion region              BJT current gain, CE configuration

MOSFET small-signal modeling                              Photovoltaic effect and basic semiconductor physics

These questions require brief, clear, and to-the-point responses.

SECTION B — Descriptive / Analytical Questions (30 Marks)

Attempt any three out of five (10 marks each).
This section tests deeper understanding of:

Effective mass and band structure curvature

Semiconductor doping calculations, Fermi level, and band diagrams

Continuity equation derivation using drift and diffusion concepts

Zener vs Avalanche breakdown

Applications of optoelectronic devices (LED, Solar cell)

Answers must include equations, diagrams, and proper explanations.

SECTION C — Long Answer / Application-Based Questions (50 Marks)

Attempt one question from each of the five groups.
These questions check advanced proficiency, problem-solving, and derivations:

Quantum Mechanics: Time-dependent & time-independent Schrödinger equation

Band Theory: Direct vs indirect band gaps, alloy variation

Carrier Statistics: Fermi-Dirac function, Einstein relation

PN Junction: Depletion width derivation, numerical problems on doped junctions

Devices:

Schottky diode                                                                              BJT Ebers-Moll model

MOS capacitor (accumulation, depletion, inversion)                    MOSFET characteristics

Each question carries 10 marks, and students must show detailed derivations, reasoning, diagrams, and relevant formulas.

Purpose of the Question Paper

The paper assesses a student's ability to:

Understand semiconductor physics deeply

Analyze device behavior under different conditions

Apply mathematical modeling to electronic devices

Draw and interpret energy band diagrams

Solve numerical problems related to doping, depletion regions, and capacitances

Explain device operations such as BJT, MOSFET, PN junctions, and optoelectronic devices