The voltage threshold for triggering an avalanche diode is typically referred to as the "breakdown voltage" or "avalanche voltage." This is the voltage at which the diode transitions from its normal, off-state behavior to a state of rapid and self-sustaining multiplication of charge carriers due to the avalanche breakdown mechanism.
Avalanche breakdown occurs in diodes with a high doping level, where a strong electric field can cause the accelerated charge carriers (electrons and holes) to gain enough energy to ionize other atoms in the crystal lattice, leading to the creation of more charge carriers. This self-sustaining process can result in a rapid increase in current through the diode, and it's typically used in applications such as voltage clamping, transient voltage suppression, and some types of voltage references.
The exact breakdown voltage varies depending on the specific design and characteristics of the diode. Avalanche diodes can be manufactured to have breakdown voltages ranging from a few volts to several hundred volts or more. It's important to note that the breakdown voltage is not an absolute threshold; rather, it's a characteristic that can have some tolerance due to manufacturing variations.
When using an avalanche diode in a circuit, it's crucial to ensure that the operating voltage remains below the breakdown voltage to avoid triggering the avalanche breakdown and causing unwanted behavior or damage to the diode.