What Is the Semiconductor PN Junction Depletion Width Calculator?
The depletion region is an insulating zone depleted of free mobile charge carriers in a semiconductor PN junction.
It creates an internal electrostatic potential barrier that blocks majority carrier diffusion in equilibrium.
How Does the Semiconductor PN Junction Depletion Width Calculator Work?
Calculates thermal voltage Vt = kb * T / q and built-in potential Vbi.
Solves Poisson's equation to find total depletion width W.
Applies charge neutrality to partition width between P-side and N-side.
Evaluates peak triangular electric field at the metallurgical interface.
Semiconductor PN Junction Depletion Width Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Poisson depletion approximation for step-junction semiconductor diode electrostatics.
How to Use the Semiconductor PN Junction Depletion Width Calculator
- Enter P-side acceptor (NA) and N-side donor (ND) concentrations in cm^-3.
- Specify semiconductor permittivity and operating temperature.
- Enter applied reverse bias voltage (0 for zero-bias equilibrium).
Step-by-Step Example Calculation
Silicon Step-Junction Diode at Zero Bias
Input Values:
Understanding Your Result
The depletion region penetrates predominantly into the lightly doped side of asymmetric junctions (e.g. p+ n).
Reverse bias widens the depletion layer, increasing breakdown voltage and decreasing junction capacitance.
Factors That Affect the Result
- Doping concentration: Higher doping shrinks depletion width and increases junction capacitance and peak field.
- Temperature: Higher temperature increases intrinsic carrier concentration ni, lowering built-in potential Vbi.
When Should You Use This Calculator?
- Designing junction field-effect transistors (JFET), PIN photodetectors, and solar cells.
- Calculating junction capacitance (C_j = eps / W) for high-frequency RF diodes.
Assumptions & Limitations
- Assumes abrupt step-junction doping profile under full depletion approximation.
- Assumes room temperature non-degenerate doping regimes.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard semiconductor physics equation validated by Sze & Ng.