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.
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.
[2] In large bipolar junction transistors, the resistance of the base layer influences the distribution of current density through the base region, especially at the emitter side.