Diode Reverse Voltage Breakdown Explained

A diode is a semiconductor device that ideally allows current to flow in only one direction (forward bias) and blocks current flow in the opposite direction (reverse bias). However, this blocking ability has a limit.

When a diode is reverse-biased, a small leakage current flows. As the reverse voltage across the diode increases, this leakage current remains relatively constant until a certain voltage is reached. This critical voltage is known as the breakdown voltage ($\text{V}_{\text{BR}}$).

If the reverse voltage exceeds the breakdown voltage ($\text{V}_{\text{R}} > \text{V}_{\text{BR}}$), the diode undergoes a phenomenon called breakdown. At breakdown, the reverse current increases very rapidly for a small increase in reverse voltage. This sudden increase in reverse current indicates that the diode's ability to block reverse current has effectively failed.

The question asks for the term describing what happens when a diode exceeds the reverse voltage, fails, and passes more current in the reverse direction. This phenomenon precisely matches the definition of diode breakdown.

Let's look at the options:

• Speed increase: This term is not related to the electrical behavior or failure mode of a diode under reverse voltage.
• Insulation: Insulation is a property of materials that resist the flow of electric current. While a diode blocks reverse current to some extent, the term doesn't describe the event of failure under excessive reverse voltage.
• Conduction: Conduction refers to the flow of electric current. While current flows during breakdown, the term 'conduction' itself doesn't specifically describe the failure mode due to exceeding reverse voltage.
• Breakdown: This term accurately describes the event where the reverse voltage limit is exceeded, leading to a rapid increase in reverse current and effective failure of the diode's blocking capability.

Therefore, the correct term for this phenomenon is breakdown.