electroluminescence

**EL** (Electroluminescence) is a **technique that analyzes light emitted from a semiconductor device when driven by electrical current** — the emission spectrum and spatial distribution reveal active regions, defects, current crowding, and device degradation. **How Does EL Work?** - **Drive**: Apply forward bias to an LED, solar cell, or semiconductor device. - **Emission**: Current flow creates electron-hole pairs that recombine radiatively. - **Detection**: Camera (CCD/CMOS) captures the spatial emission pattern. Spectrometer analyzes the spectrum. - **Dark Areas**: Regions with no emission indicate defects, cracks, or inactive areas. **Why It Matters** - **Solar Cell Testing**: Dark spots in EL images reveal cracks, shunts, and inactive regions in solar cells. - **LED Characterization**: Maps current distribution and identifies hot spots or defective regions. - **Reliability**: EL changes during aging tests reveal degradation mechanisms. **EL** is **the device's own light show** — watching where and how a device emits light to diagnose its health and quality.