Which semiconductor device emits light when current passes through it?

Which semiconductor device emits light when current passes through it?

• A. Light Emitting Diodes
• B. Photodiodes
• C. Zener Diodes
• D. Rectifier Diodes

Answer: (A)

Light emission from a semiconductor occurs when radiative recombination happens in a forward-biased PN junction, releasing photons as electrons recombine with holes. Devices built to emit light use materials that produce photons when current flows through them. That’s exactly how a light emitting diode works: forward current drives electrons into the junction so they drop across the bandgap and emit light. In contrast, photodiodes are designed to detect light and generate current when photons hit the junction; they don’t emit light as part of their normal operation. Zener diodes rely on reverse breakdown to regulate voltage, not light emission. Rectifier diodes are used to convert alternating current to direct current and also don’t emit light in standard use.

Light emission from a semiconductor occurs when radiative recombination happens in a forward-biased PN junction, releasing photons as electrons recombine with holes. Devices built to emit light use materials that produce photons when current flows through them. That’s exactly how a light emitting diode works: forward current drives electrons into the junction so they drop across the bandgap and emit light.

In contrast, photodiodes are designed to detect light and generate current when photons hit the junction; they don’t emit light as part of their normal operation. Zener diodes rely on reverse breakdown to regulate voltage, not light emission. Rectifier diodes are used to convert alternating current to direct current and also don’t emit light in standard use.