Varshni Bandgap Calculator
Evaluate the Varshni temperature dependence of a semiconductor bandgap: Eg(T)=Eg0 - alpha·T²/(T+beta), using a logarithmic evaluation that avoids overflowing T². The coefficients are material-specific empirical fit parameters; extrapolation beyond their fitted temperature range can produce nonphysical results.
Description
Calculate temperature-dependent semiconductor bandgap with material-specific Varshni parameters.
Evaluate the Varshni temperature dependence of a semiconductor bandgap: Eg(T)=Eg0 - alpha·T²/(T+beta), using a logarithmic evaluation that avoids overflowing T². The coefficients are material-specific empirical fit parameters; extrapolation beyond their fitted temperature range can produce nonphysical results.
When to use Varshni Bandgap Calculator
- Calculate temperature-dependent semiconductor bandgap with material-specific Varshni parameters.
- Compare fabrication or device scenarios while holding coefficients and unit conventions constant.
- Check a hand calculation before moving to a higher-fidelity process, circuit, or TCAD model.
How the calculation works
At high temperature the correction approaches an approximately linear αT dependence; α and β cannot be transferred blindly between materials.1
Eg(T) = Eg(0) − αT²/(T+β) Interpreting the result
At high temperature the correction approaches an approximately linear αT dependence; α and β cannot be transferred blindly between materials.
Assumptions and limitations
- Varshni parameters are empirical over a fitted range, and extrapolation can produce negative, nonphysical bandgaps.
- Use parameters measured for the same material, geometry, temperature, and operating regime whenever the result informs engineering work.
References
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Properties of Semiconductor Alloys — University of Illinois