Introduction to Physics: Core Concepts

• Physics is the natural science of matter and its motion through space and time.
• Physics studies energy and force.
• Physics seeks to understand the behavior of the universe.

Core Concepts in Physics

• Classical mechanics describes the motion of macroscopic objects, from projectiles to machinery parts, and astronomical objects like spacecraft and galaxies.
• Thermodynamics studies heat, work, and energy, defining variables like temperature, entropy, and pressure.
• Electromagnetism studies interactions of electrically charged particles and magnetic fields, including electric and magnetic fields and electromagnetic radiation like light.
• Quantum mechanics describes matter and energy at atomic and subatomic levels, including wave-particle duality and quantum entanglement.
• Relativity, including special and general relativity, describes spacetime and gravity, with applications from cosmology to GPS.

Semiconductor Physics

• Semiconductors' electrical conductivity falls between that of conductors and insulators.
• Conductivity can be controlled, ideal for electronic devices.
• Silicon (Si), germanium (Ge), and gallium arsenide (GaAs) are common semiconductor materials.

Energy Bands

• In solids, electron energies exist within specific bands.
• Energy gaps separate these bands where no electron states exist.
• The valence band is the highest occupied band, and the conduction band is next above it.

Electrons and Holes

• Electrons are negatively charged particles carrying current in the conduction band.
• Holes are vacancies from electrons in the valence band, behaving as positive particles
• Both electrons and holes contribute to current flow in semiconductors.

Doping

• Doping modifies a semiconductor's electrical properties by adding impurities.
• N-type doping adds donor impurities for extra electrons in the conduction band, increasing conductivity.
• P-type doping adds acceptor impurities, creating holes in the valence band, and increasing conductivity.

P-N Junctions

• A p-n junction forms when p-type and n-type semiconductors are joined.
• Electrons from the n-side diffuse to the p-side, and holes from the p-side diffuse to the n-side.
• Diffusion creates a depletion region with few free charge carriers and an electric field.

Biasing

• Biasing is applying voltage across a p-n junction.
• Forward bias connects the p-side to positive voltage and the n-side to negative, reducing the depletion region and allowing current flow.
• Reverse bias connects the p-side to negative voltage and the n-side to positive, widening the depletion region and blocking current flow.

Semiconductor Devices: Diodes

• A diode is a two-terminal device allowing current flow in one direction, based on a p-n junction.
• Diodes are for rectification (AC to DC), signal demodulation, and voltage regulation.

Transistors

• Transistors are three-terminal devices amplifying or switching electronic signals and electrical power.
• Bipolar Junction Transistors (BJTs) are current-controlled devices with two p-n junctions.
• Field-Effect Transistors (FETs) are voltage-controlled devices using an electric field to control current flow.
• MOSFETs (Metal-Oxide-Semiconductor FETs) are FETs widely used in digital circuits for low power consumption and high integration density.

Integrated Circuits (ICs)

• Integrated circuits are miniaturized electronic circuits with transistors, diodes, resistors, and capacitors on a semiconductor chip.
• ICs enable complex electronic functions in a small package.

Optoelectronic Devices

• Optoelectronic devices convert electrical energy into light or vice versa.
• Light-Emitting Diodes (LEDs) emit light when current passes through them.
• Photodiodes detect light by generating a current when exposed to photons.
• Solar cells convert sunlight into electricity using the photovoltaic effect.

Semiconductor Manufacturing

• Semiconductor manufacturing includes crystal growth, wafer fabrication, photolithography, etching, doping, and packaging.
• Cleanroom environments prevent contamination during manufacturing.

Applications

• Semiconductors are in computers, smartphones, consumer electronics, automotive systems, and industrial automation.
• Semiconductors are crucial in renewable energy systems like solar panels and medical devices.

Advanced Semiconductor Materials

• Materials like gallium nitride (GaN) and silicon carbide (SiC) are researched for high-power and high-frequency applications.
• These materials have higher breakdown voltage, higher operating temperature, and better thermal conductivity.

Physics is the natural science that studies matter, its motion, and behavior through space and time, including energy and force. It aims to understand the fundamental behaviors of the universe. Key areas include classical mechanics, thermodynamics, electromagnetism and quantum mechanics.