Ballistic Mean Free Path Calculator
Estimate the ballistic mean free path from low-field mobility using λ = (μ·Vt/vsat)·1e7 with thermal voltage Vt=0.02585 V (300 K) and saturation velocity vsat=1e7 cm/s (λ[nm]=μ·0.02585). Input mobility μ>0 cm²/V·s must be the low-field, non-degenerate value; rpm vs linear-velocity and per-area vs total distinctions do not apply. Model assumes Maxwell-Boltzmann statistics and constant vsat, valid only near 300 K as a quasi-ballistic estimate.
Description
Estimate a 300 K mobility-derived carrier mean-free-path scale using fixed thermal voltage and saturation velocity.
Estimate the ballistic mean free path from low-field mobility using λ = (μ·Vt/vsat)·1e7 with thermal voltage Vt=0.02585 V (300 K) and saturation velocity vsat=1e7 cm/s (λ[nm]=μ·0.02585). Input mobility μ>0 cm²/V·s must be the low-field, non-degenerate value; rpm vs linear-velocity and per-area vs total distinctions do not apply. Model assumes Maxwell-Boltzmann statistics and constant vsat, valid only near 300 K as a quasi-ballistic estimate.
When to use Ballistic Mean Free Path Calculator
- Estimate a 300 K mobility-derived carrier mean-free-path scale using fixed thermal voltage and saturation velocity.
- 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
With the fixed constants, the numerical result in nanometers is μ·0.02585 for mobility in cm²/V·s.
λ = μ · Vthermal / vsat Interpreting the result
With the fixed constants, the numerical result in nanometers is μ·0.02585 for mobility in cm²/V·s.
Assumptions and limitations
- A rigorous mean free path requires the relevant carrier velocity and scattering time; fixed 300 K thermal voltage and saturation velocity make this a screening estimate.
- Use parameters measured for the same material, geometry, temperature, and operating regime whenever the result informs engineering work.