Lesson plan
Current crowding
Current crowding (also current crowding effect, or CCE) is a nonuniform distribution of current density through a conductor or semiconductor, especially in the vicinity of electrical contacts and over p–n junctions. Current crowding is one of the factors limiting the efficiency of light-emitting diodes. Materials with low mobility of charge carriers (e.g., aluminium gallium indium phosphide (AlGaInP)) are especially prone to current crowding phenomena. It is the dominant loss mechanism in some LEDs, where the current densities, especially around the P-side contacts, reach an area of the emission characteristics with lower brightness/current efficiency. Current crowding can lead to localized overheating and formation of thermal hotspots, in catastrophic cases leading to thermal runaway. Nonhomogenous distribution of current also aggravates electromigration effects and the formation of voids (see, e.g., the Kirkendall effect). Formation of voids causes localized nonhomogeneity of current density, and the increased resistance around the void causes further localized temperature rise, which in turn accelerates the formation of the void. Conversely, localized lowering of current density may lead to deposition of the migrated atoms, leading to further lowering of current density, further deposition of material, and formation of hillocks, which may cause short circuits.…
Article summary
Current crowding (also current crowding effect, or CCE) is a nonuniform distribution of current density through a conductor or semiconductor, especially in the vicinity of electrical contacts and over p–n junctions. Current crowding is one of the factors limiting the efficiency of light-emitting diodes. Materials with low mobility of charge carriers (e.g., aluminium gallium indium phosphide (AlGaInP)) are especially prone to current crowding phenomena. It is the dominant loss mechanism in some LEDs, where the current densities, especially around the P-side contacts, reach an area of the emission characteristics with lower brightness/current efficiency. Current crowding can lead to localized overheating and formation of thermal hotspots, in catastrophic cases leading to thermal runaway. Nonhomogenous distribution of current also aggravates electromigration effects and the formation of voids (see, e.g., the Kirkendall effect). Formation of voids causes localized nonhomogeneity of current density, and the increased resistance around the void causes further localized temperature rise, which in turn accelerates the formation of the void. Conversely, localized lowering of current density may lead to deposition of the migrated atoms, leading to further lowering of current density, further deposition of material, and formation of hillocks, which may cause short circuits.…
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.