Avalanche breakdown is a phenomenon that occurs in semiconductors when a high electric field causes a rapid increase in charge carriers. This process begins when a single electron gains enough energy to collide with an atom, releasing additional electrons. These newly freed electrons can then cause further collisions, leading to a chain reaction that significantly increases current flow. This effect is commonly observed in devices like diodes and transistors, where it can lead to device failure if not properly managed. Avalanche breakdown is characterized by a sudden rise in current, which can damage the semiconductor material if the voltage exceeds a certain threshold.