C-V Profiling (Capacitance-Voltage Profiling) is a semiconductor characterization technique that measures the capacitance of a MOS structure or junction as a function of applied voltage — extracting doping profiles, oxide thickness, interface trap density, and flatband voltage.

How Does C-V Profiling Work?

• Structure: MOS capacitor, Schottky diode, or p-n junction.
• Measurement: Apply DC bias voltage while measuring small-signal AC capacitance.
• Regions: Accumulation (max $C$), depletion (decreasing $C$), inversion (min $C$ or recovery depending on frequency).
• Doping Profile: $N(W) = -2 / (q epsilon_s A^2 cdot d(1/C^2)/dV)$.

Why It Matters

• Gate Oxide: $t_{ox} = epsilon_{ox} A / C_{max}$ — directly measures gate oxide thickness.
• Doping: Non-destructive depth profiling of doping concentration.
• Interface Quality: $D_{it}$ (interface trap density) extracted from frequency dispersion of the C-V curve.

C-V Profiling is the electrical X-ray for MOS structures — extracting oxide thickness, doping profiles, and interface quality from a single voltage sweep.