What causes a junction diode to fail from excessive current?

When electrical current flows through a junction diode, it encounters a small amount of internal resistance, exhibited as a forward voltage drop. As the current passes through this resistance, power is dissipated in the form of heat, according to the power formula P = I x E. If the current becomes excessive, the amount of heat generated will quickly exceed the physical package's ability to dissipate it. This causes the internal temperature of the semiconductor junction to rise to a critical level, ultimately melting or permanently damaging the silicon structure. Other options focus on different failure modes or operational characteristics. Excessive inverse voltage causes a diode to fail through avalanche breakdown, not excessive forward current, while charge carrier depletion and insufficient forward voltage merely prevent the diode from conducting.