Ontological Layer: Mobile Entities
Charge Carriers
The Mechanics of Semiconductor Current
The Actors Within the Lattice
Energy bands define where electrons can exist; Charge Carriers are the entities that actually move. This realm categorizes the dual nature of semiconductor conduction—electrons and holes—tracking how they are generated, how they randomly scatter or drift under forces, and how their lifespan dictates the speed of modern electronics.
The 12 Carrier Nodes
Vertical Ontology: From Generation to Total Current
The Two Carriers
- Charge Carrier Concept
- Electrons (Negative Charge)
- Holes (Effective Positive Charge)
- Physical vs Abstract Motion
Majority vs Minority
- N-Type: e⁻ Majority, h⁺ Minority
- P-Type: h⁺ Majority, e⁻ Minority
- Dependence on Doping Type
- Role in Junction Formation
Carrier Concentration
- Electron Concentration (n)
- Hole Concentration (p)
- Intrinsic Concentration (ni)
- Equilibrium Carrier State
Mass-Action & Neutrality
- Mass-Action Law (np = ni²)
- Charge Neutrality Equation
- Donor & Acceptor Contributions
- Degenerate vs Non-Degenerate
Generation & Recombination
- Thermal & Optical Generation
- Electron-Hole Pair Creation
- Radiative vs Non-Radiative Recomb
- Gen-Recomb Equilibrium State
Excess Carriers & Lifetime
- Excess Carrier Injection (Δn, Δp)
- Carrier Lifetime (τ)
- Minority-Carrier Lifetime
- Return to Equilibrium
Mobility & Scattering
- Carrier Mobility (μe, μh)
- Phonon (Lattice) Scattering
- Impurity Scattering
- Mobility Temperature Dependence
Drift vs Diffusion
- Drift: Electric Field Driven
- Diffusion: Concentration Driven
- Carrier Velocity & Drift Velocity
- Bridge to Realm 05 (Transport)
Concentration Profiles
- Spatial Distribution [n(x), p(x)]
- Minority-Carrier Profiles
- Concentration Gradients
- Driving Force for Diffusion
Carrier Injection
- Low-Level vs High-Level Injection
- Injected Carriers at Boundaries
- Carrier Accumulation & Depletion
- Foundation for Diode Action
Total Semiconductor Current
- Electron Current (Jn)
- Hole Current (Jp)
- Summing Drift and Diffusion
- Total Current Density Equations
12 — Charge-Carrier Problem Solving
Bringing the physics into engineering mathematics. Solving for exact carrier concentrations under varying doping levels, calculating exponential decay of excess carriers, and determining total current density from electric fields and gradients.