A form of catastrophic destructive breakdown in bipolar junction transistors. Local heating inside the transistor increases the intrinsic carrier concentration, causing the local resistivity to fall. This enables a higher current density to flow, causing further heating. The current multiplication is rapid, leading to melting of the semiconductor and destruction of the transistor. This phenomenon occurs at high collector voltages and modest collector currents: it should not be confused with avalanche breakdown – another operational limit in bipolar transistors – which is a voltage-induced effect.