Concept:When electron-hole recombination occurs across the bandgap, the energy of the emitted photon directly corresponds to the forbidden energy gap (\( E_g \)) of the semiconductor.
Formula:$$\lambda = \frac{h c}{E_g} = \frac{1240\text{ eV}\cdot\text{nm}}{E_g\text{ (in eV)}}$$
Solution:- Different compound semiconductors have distinct band gaps: GaAs emits infrared (\( \approx 1.4\text{ eV} \)), GaAsP emits red/amber, and GaN/InGaN emits blue light (\( \approx 3.4\text{ eV} \)).
- Therefore, the material's energy bandgap \( E_g \) determines the wavelength and color of emitted light.
Why other options are incorrect:- Option A: Forward current controls optical intensity (brightness), not the emission wavelength.
- Option B: Packaging protects the die and may focus light, but it does not determine photon bandgap emission.
- Option D: Reverse breakdown rating is unrelated to forward-bias radiative recombination.
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