Semiconductor Physics

Materials & Crystal

• Semiconductor Materials (Si, Ge, GaAs)
• Atomic Structure & Valence Electrons
• Covalent Bonding Mechanism
• Crystal Lattice Structure

Energy Bands & Gaps

• Energy States in Solids
• Valence Band & Conduction Band
• The Forbidden Energy Gap (Eg)
• Thermal Excitation & Transitions

Material Classification

• Conductors (Overlapping Bands)
• Insulators (Wide Band Gap)
• Semiconductors (Narrow Band Gap)
• Conductivity Magnitude Comparisons

Intrinsic & Extrinsic

• Pure (Intrinsic) Semiconductors
• Doping (Extrinsic) Process
• Donor Impurities (Pentavalent, N-Type)
• Acceptor Impurities (Trivalent, P-Type)

Charge Carriers

• Electrons (n) & Holes (p)
• Majority vs Minority Carriers
• Intrinsic Carrier Concentration (ni)
• Generation & Recombination Rates

Carrier Transport

• Drift Current (Electric Field Driven)
• Carrier Mobility (μ)
• Diffusion Current (Concentration Driven)
• Einstein Relationship (D/μ = kT/q)

Conductivity & Resistivity

• Semiconductor Conductivity (σ)
• Dependence on n, p, and Mobility
• Resistivity (ρ) Calculations
• Temperature Dependence of Resistance

The Fermi Level

• Fermi Energy & Occupancy Probability
• Fermi-Dirac Distribution Function
• Maxwell-Boltzmann Approximation
• Fermi Level Shifts (N-type vs P-type)

Mass-Action & Neutrality

• Mass-Action Law (n × p = ni²)
• Charge Neutrality Equation
• Compensation Doping
• Equilibrium Carrier Concentration Math

Direct vs Indirect Gaps

• E-k Diagrams (Energy vs Momentum)
• Direct Band Gap (GaAs, Optical)
• Indirect Band Gap (Si, Ge, Phonons)
• Applications in LEDs and Lasers

Advanced Statistics

• Density of States [g(E)]
• Effective Mass of Carriers (m*)
• Quantum Effects Overview
• Excess Carriers & Carrier Lifetime (τ)

12 — Physics Problem Solving

Applying the formulas. Calculating exact electron and hole populations, determining the position of the Fermi level relative to band edges, and solving conductivity problems across different temperatures and doping concentrations.