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Effective Mass Parabolic Band Energy

Effective Mass Parabolic Band Energy
\[E=\frac{\hbar^2 k^2}{2m^\ast}\]

Variables

Eelectron energy (J)
hbar[ℏ]reduced Planck constant (J·s)
kwave vector magnitude (1/m)
meff[m*]effective mass of electron (kg)

Description

What is this formula?

The effective mass parabolic band energy equation describes the energy of an electron in a semiconductor or crystal lattice using the effective mass approximation. Near the conduction or valence band extrema, the energy-momentum relation behaves approximately like a parabola.


When to use it

This formula is used in semiconductor physics, band structure analysis, and charge carrier transport calculations. It is especially useful when electrons interact with a periodic crystal lattice and cannot be treated as completely free particles.


Example

An electron in a semiconductor has:


k = 5.0×10^8 1/m

m* = 0.067×9.11×10^-31 kg


Using:


E = (ℏ²k²)/(2m*)


Where:


ℏ = 1.055×10^-34 J·s


Substitution:


E = ((1.055×10^-34)² × (5.0×10^8)²) / (2 × 0.067 × 9.11×10^-31)


Result:


E ≈ 2.28×10^-20 J


Applications

- Semiconductor band structure analysis

- Electron transport modeling

- Effective mass approximation

- Quantum well calculations

- Solid state physics

- Nanoelectronics

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