What limits the maximum forward current in a junction diode?

When current flows through a junction diode in the forward direction, power is dissipated as heat due to the diode's inherent forward voltage drop. If the current becomes too high, the heat generated exceeds the component's ability to dissipate it safely into the surrounding environment. This excess heat causes the internal junction temperature to rise rapidly. If the temperature exceeds the thermal limits of the semiconductor material, the junction will melt or suffer permanent degradation. Therefore, it is the maximum allowable junction temperature that ultimately restricts how much continuous forward current a diode can handle. Peak inverse voltage (PIV) is a rating for reverse-bias conditions, and while back EMF or forward voltage play roles in circuit behavior, they are not the physical limiting factors for continuous current handling like thermal destruction is.