Calculator Inputs
Plotly Graph
The graph shows how the temperature-adjusted breakdown voltage changes as effective doping varies around your selected design point.
Example Data Table
| Material | Model | εr | Ecrit (V/cm) | Doping N (cm-3) | Estimated VBR at 25 °C (V) |
|---|---|---|---|---|---|
| Silicon (Si) | One-Sided Abrupt | 11.80 | 3.00e+5 | 1.0000e+16 | 29.3449 |
| Germanium (Ge) | One-Sided Abrupt | 16.00 | 1.50e+5 | 5.0000e+15 | 19.8949 |
| Gallium Arsenide (GaAs) | One-Sided Abrupt | 13.10 | 4.00e+5 | 8.0000e+15 | 72.3952 |
| 4H-Silicon Carbide (4H-SiC) | One-Sided Abrupt | 9.70 | 2.50e+6 | 1.0000e+16 | 1,675.1746 |
Formula Used
VBR,ref = (εs × Ecrit²) / (2 × q × N)
VBR,ref = (εs × Ecrit²) / (q × N)
WBR = (εs × Ecrit) / (q × N)
VBR(T) = VBR,ref × [1 + α × (T - Tref)]
Vsafe = VBR(T) / Safety Factor
Where:
- εs = semiconductor permittivity = εr × ε0
- Ecrit = critical electric field at avalanche onset
- q = electronic charge
- N = effective doping concentration
- α = temperature coefficient expressed as a decimal fraction per degree
How to Use This Calculator
- Select a material preset or choose the custom option.
- Pick the junction model that best matches your device structure.
- Enter relative permittivity and the critical electric field.
- Input the effective doping concentration in cm-3.
- Set operating temperature, reference temperature, and temperature coefficient.
- Choose a safety factor to create a conservative operating limit.
- Press Calculate Breakdown to display results above the form.
- Review the graph, export the CSV, or generate the PDF summary.
FAQs
1) What does avalanche breakdown voltage mean?
It is the reverse voltage where carriers gain enough energy to create additional electron-hole pairs by impact ionization. Beyond this point, current rises sharply and device stress increases rapidly.
2) Why does higher doping usually reduce breakdown voltage?
Heavier doping narrows the depletion region. That lets the electric field reach the critical value at a lower applied voltage, so avalanche begins sooner.
3) When should I use the one-sided junction model?
Use it when one side of the junction is much more heavily doped than the other. In that case, most depletion expansion occurs in the lightly doped side.
4) What is the purpose of the temperature coefficient?
It adjusts the reference breakdown voltage for operating temperature. Avalanche breakdown in many devices rises slightly with temperature, though the exact coefficient depends on material and structure.
5) Is this calculator valid for every semiconductor device?
No. It gives a strong engineering estimate for abrupt-junction behavior. Real devices may also depend on curvature, edge termination, lifetime control, trap states, and manufacturing details.
6) Why is 4H-SiC showing much larger breakdown voltage?
4H-SiC supports a far higher critical electric field than silicon. That allows much larger blocking voltage for the same doping level and greatly benefits high-power devices.
7) What should I enter for effective doping?
For one-sided designs, enter the lightly doped drift or base region concentration. For symmetric abrupt designs, use the representative equal-side concentration assumed by the model.
8) Why include a safety factor in reverse-voltage design?
A safety factor helps prevent operation too close to breakdown under temperature shifts, tolerances, transient spikes, and model uncertainty. It creates a more reliable design margin.