Analyze semiconductor interface states using flexible engineering inputs. Generate results, tables, exports, and response curves. Improve device characterization with clear calculations and visual insights.
Use the conductance peak method for measured Gp/ω data, or use the subthreshold swing method when MOSFET transfer data is available. The input grid is three columns on large screens, two on medium screens, and one on mobile.
The conductance approach estimates interface trap density from the peak value of the normalized conductance response. A widely used approximation is:
Dit = (Gp/ω)max / (0.402 × q × A)
Where Dit is in cm-2 eV-1, q is electron charge, A is device area in cm2, and (Gp/ω)max is the peak conductance term in farads.
The integrated state density over an energy interval is estimated by:
Nit,integrated = Dit × ΔE
For MOSFET transfer curves, the ideal thermal limit is calculated first:
Sideal = ln(10) × k × T / q
The trap capacitance estimate becomes:
Cit = Cox × (SS / Sideal - 1) - Cd
Then the interface trap density is:
Dit = Cit / q
Here SS is measured subthreshold swing, Cox is oxide capacitance per unit area, and Cd is depletion capacitance per unit area.
Select the calculation method. Choose conductance when you have peak Gp/ω data, or choose subthreshold when you want to estimate Dit from transfer curve slope.
Enter device area, energy limits, and graph density. The energy interval is used to estimate the integrated interface states across the selected trap window.
Provide the method-specific data. Conductance mode accepts either direct Gp/ω input or Gp with frequency. Subthreshold mode accepts direct Cox or oxide thickness with dielectric constant.
Click the calculate button. The result appears above the form, below the header, exactly as requested. Export the result table to CSV or capture the result panel as PDF.
| Method | Input Set | Key Measured Value | Computed Dit | Comment |
|---|---|---|---|---|
| Conductance peak | A = 1.0e-4 cm², ΔE = 0.60 eV | (Gp/ω)max = 5.2e-10 F at 10 kHz | 8.077e13 cm⁻² eV⁻¹ | Represents a high-density interface state condition. |
| Conductance peak | A = 2.5e-4 cm², ΔE = 0.40 eV | (Gp/ω)max = 1.4e-10 F at 5 kHz | 8.702e12 cm⁻² eV⁻¹ | Lower response with a larger active device area. |
| Subthreshold swing | Cox = 1.15 µF/cm², Cd = 0.08 µF/cm² | SS = 92 mV/dec at 300 K | 3.422e12 cm⁻² eV⁻¹ | Moderate degradation from the ideal swing limit. |
| Subthreshold swing | tox = 12 nm, k = 3.9, Cd = 0.05 µF/cm² | SS = 75 mV/dec at 300 K | 1.553e12 cm⁻² eV⁻¹ | Closer to ideal channel control and lower interface trapping. |
It represents the density of electronic trap states at the semiconductor interface, usually near the oxide boundary. Larger values often indicate poorer interface quality, degraded channel control, higher threshold instability, and worse subthreshold behavior in electronic devices.
Use the conductance method when you have capacitance-conductance test data and a clear peak in Gp/ω. It is widely used for MOS capacitor studies and is especially useful when frequency-domain measurements are reliable.
It is helpful when you have MOSFET transfer data but no detailed conductance sweep. The method links measured subthreshold slope to excess capacitance at the interface and then estimates Dit from that excess term.
Area is required for the conductance-based Dit calculation because the response must be normalized to active device size. It is also used to estimate the total number of trap states contained in the selected energy interval.
If the measured swing is very close to the ideal thermal limit, or if depletion correction is large, the calculated trap capacitance can become negative. In that case, the calculator limits Dit to zero and shows a notice.
Enter the interface state energy span that matches your characterization objective. A narrow range is useful for localized analysis, while a wider range produces an integrated trap estimate across more of the bandgap interface region.
Yes. In subthreshold mode, you can either enter Cox directly or derive it from oxide thickness and dielectric constant. This is useful when physical stack dimensions are known but the capacitance value is not.
The graph visualizes the chosen model response. Conductance mode shows the frequency response around the selected peak, while subthreshold mode shows how Dit changes as subthreshold swing varies around your operating point.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.