Modern Physics : Semiconductor - Electronics Devices

Explore how semiconductors, mid-way between conductors and insulators, power everyday electronics—from calculators to televisions and refrigerators—through solid-state devices, integrated circuits, diodes, and transistors.

Explore how valence bands and conduction bands determine electrical conduction in metals, semiconductors, and insulators, through energy gaps and electron excitation.

Analyze the electrical conductivity of a semiconductor by combining electrons and holes. Explore extrinsic semiconductors, mobility, and current density under electric fields.

Explore the classification of semiconductors into elemental, compound, and organic types, with examples like silicon, germanium, gallium arsenide, and cadmium sulfide, and their uses in displays and photovoltaic cells.

Learn how energy bands form in solids, with a focus on semiconductors like silicon, including valence and conduction bands, and the energy gap that governs electrical conduction.

The lecture explains how electron shells form energy bands in conductors, using iron’s configuration to show how absorbed energy frees outer electrons to conduct electricity.

Explore intrinsic semiconductors as pure silicon or germanium, explain covalent bonds, octet stability, and how heating creates free electrons for conduction.

Explore matter and the three states—gas, liquid, and solid—using everyday examples and their properties. Compare crystalline and amorphous solids, noting fixed shape, fixed volume, and intermolecular forces.

Explore crystalline solids with a regular atomic arrangement and a sharp melting point. See how refractive index and other properties vary with direction, revealing anisotropy and long-range order.

Explore how Bravais lattices organize crystal structures by edge length and angles alpha, beta, gamma, and survey seven lattice types from cubic to hexagonal, including monoclinic, rhombohedral, and rhombic forms.

Explore cubic lattices in semiconductors by detailing a cube’s six faces, eight lattice points, and twelve edges. Compare three lattice types, including body-centered cubic and space-centered cubic structures.

Examine the simple cubic cell, twelve edges and eight corner points; corners contribute one-eighth of an atom, yielding one atom per cell with coordination number six and packing efficiency 52.4%.

Study the body centered cubic cell in semiconductors and electronic devices, with a central atom, eight corner atoms, coordination number eight, packing efficiency 68 percent and 32 percent void.

Explore the face-centered cubic cell, with six face-centered atoms and eight corner lattice points, yielding a 12-fold coordination and about 74% packing efficiency.

Learn how group iii and group v dopants, such as aluminium and phosphorus, convert intrinsic silicon into extrinsic semiconductors and establish n-type and p-type materials, with n_i^2 = n p.

Introduce extrinsic n-type semiconductors by doping silicon with phosphorus, creating free electrons as majority carriers and holes as minority carriers, boosting conductivity.

Explore how p-type semiconductors form by introducing dopants like aluminium into silicon, creating holes as majority carriers and electrons as minority carriers, and preview valence and conduction bands.

Explore how n-type and p-type semiconductors form, with donor and acceptor impurities creating energy levels that lower the energy gap and enable conduction from the balance band or donor level.

Explore how p-type and n-type semiconductors meet at a junction, forming a depletion region that blocks conductivity. Understand how biasing enables conduction, with details to follow in the next lecture.

Analyze the pn junction diode, its depletion region and potential barrier, and how doping level and temperature affect width; note silicon's 0.7 V and germanium's 0.3 V.

Explore biasing of a semiconductor, including forward and reverse biasing, depletion region, potential barrier, and how P-type and N-type materials connect to a DC supply in a junction diode.

Explore forward biasing of a p-n junction diode connected to a battery, noting the low forward resistance and the sudden current surge as the depletion region breaks.

Explore how a p-n junction diode acts as a half-wave rectifier, converting ac to dc by conducting on the positive half-cycle (forward bias) and blocking on the negative (reverse bias).

Discover how a p-n junction diode serves as a full wave rectifier, converting ac to dc with two diodes and a transformer, while explaining forward and reverse bias.

Discover how an AC supply becomes DC by using a transformer, rectifier, and ripple factor, then filter circuit and capacitor smooth the output before regulation for a stable DC output.

Learn how the zener diode, heavily doped with a thin depletion region, uses reverse breakdown to act as a voltage regulator that keeps the output constant.

Explore how photodiodes convert light into electric current via a depletion layer, minority carriers, and photocurrent, and analyze the i–v characteristics and dark versus saturation current.

Understand how a light emitting diode (LED) works with forward current and depletion layer, emitting monochromatic light, and apply it in TVs, mobile screens, and lighting.

Explore how solar cells convert light energy to electricity via a p-n junction, with anti-reflection coating and electron-hole pair generation.

Explore the transistor basics, including emitter, base, and collector terminals; junctions, doping levels, thickness, and forward and reverse bias leading to active region.

Explore transistor configurations, including common emitter, common base, and common collector, and examine emitter, base, and collector currents, alpha (voltage gain), and beta.

Analyze how analog and digital signals move through analog and digital circuits. Learn how logic gates like and, or, not, and exclusive or control signal flow and reduce energy dissipation.

Explore common emitter transistor characteristics, including input and output characteristics, and input and output resistance, with biasing and the active region in focus.

Explore how logic gates control electric circuits, focusing on and gate, or gate, and not gate, their symbols, truth tables, and when outputs are high or low.

Analyze nand, not, and xor gates and their representations. Explore symbolic expressions and switching tables to see how inputs determine outputs.