Ontological Layer: Electrostatic Structure
PN Junction
The Birth of the Semiconductor Device
The Self-Forming Barrier
A PN junction is not merely p-type material touching n-type material. It is a dynamic, self-forming electrostatic structure born from conflict. Driven by concentration gradients, carriers diffuse across the boundary, leaving behind uncovered, immobile ions. This creates a built-in electric field that perfectly opposes further diffusion, achieving a delicate equilibrium.
P-TYPE +
N-TYPE →
GRADIENT →
DIFFUSION →
RECOMBINATION →
IMMOBILE IONS →
DEPLETION REGION →
E-FIELD →
BUILT-IN POTENTIAL →
EQUILIBRIUM
The 63 Junction Nodes
Categorized Structural & Behavioral Map
GROUP I
Junction Concept & Formation
- 01 Junction Concept
- 02 p-Type Region / 03 n-Type Region
- 04 Joining Materials
- 05 Concentration Difference
- 06-08 Carrier Diffusion
- 09 Recombination Near Junction
- 10 Immobile Ions
The Depletion Region
- 11 Depletion Region
- 12 Space-Charge Region
- 13 Built-In Electric Field
- 14 Built-In Potential
- 15 Barrier Potential
- 25 Depletion Width
- 26 Depletion Charge
Equilibrium & Energy
- 16 Thermal Equilibrium
- 17 Drift / 18 Diffusion at Eq.
- 19 Current Balance (Net = 0)
- 20 Energy-Band Diagram
- 21 Band Bending
- 22 Equilibrium Fermi Level
Biasing Mechanics
- 28 Reverse-Biased Junction
- 29 Reverse-Bias Depletion Width
- 30 Reverse-Bias Electric Field
- 31 Forward-Biased Junction
- 32 Forward-Bias Barrier Reduction
- 33-35 Carrier Injection Mechanisms
Junction Current
- 36 Junction Current Origin
- 37 Diode Current Equation
- 38 Ideal Junction Behaviour
- 39 Non-Ideal Behaviour
- 40 Temperature Dependence
- 41 Reverse Saturation Current
Breakdown Mechanisms
- 42 Junction Breakdown
- 43 Zener Breakdown
- 44 Avalanche Breakdown
- 45 Breakdown Voltage (Vbr)
- 46 Junction Leakage
Dynamics & Capacitance
- 27 Junction Capacitance
- 47 Gen-Recomb in Junction
- 48 Transit Time
- 49 Charge Storage
- 50 Junction Switching Time
Physical Profiles
- 23 Potential / 24 E-Field Profiles
- 51 Abrupt Junction
- 52 Graded Junction
- 53 Linearly Graded
- 54 One-Sided / 55 Symmetrical
Mathematical Analysis
Vbi = (kT/q)ln(NaNd/ni²)
W = √[2ε/q(1/Na+1/Nd)Vbi]
Id = Is[exp(qV/kT) - 1]
- 56 Potential vs Doping
- 57-58 Depletion Width vs Doping/Bias
- 59 Capacitance vs Bias
- 60-61 Current & Characteristics
- 62-63 Numerical Problem Solving