An LED made from a GaAsP p–n junction has an energy gap of 1.9 eV. What wavelength does its emitted light approximately have?
Options

Question

An LED made from a GaAsP p–n junction has an energy gap of 1.9 eV. What wavelength does its emitted light approximately have?

G1 Physics · Accepted Answer

Radiated photon energy is approximately the semiconductor band gap: E = hc/λ. In convenient units hc = 1240 eV·nm. Thus λ = 1240/1.9 nm = 652.6 nm ≈ 654 nm. Final answer: Option B.