capacitance-voltage profiling

**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.