๐ Diode Directionality and Breakdown Behavior
๐ง Motivation
โน๏ธ
Why we care
Diodes are designed to favor current flow in one direction (forward bias), but under extreme reverse bias, they can conduct in the opposite directionโtriggering breakdown mechanisms that are crucial in voltage regulation and protection circuits.
๐ Directional Behavior of a PN Junction Diode
| Bias Type | Behavior | Carrier Movement |
|---|---|---|
| Forward Bias | Easy current flow (P โ N) | Electrons from N recombine with holes in P |
| Reverse Bias | Minimal current (leakage only) | Minority carriers drift slowly |
| Breakdown | Sudden large reverse current | High-energy carriers trigger bond breakage |
โก Breakdown Mechanisms
๐ฌ Zener Breakdown
- Occurs in heavily doped diodes with narrow depletion regions
- High electric field causes quantum tunneling of electrons
- Used intentionally in Zener diodes for voltage regulation
๐ช๏ธ Avalanche Breakdown
- Occurs in lightly doped diodes with wider depletion regions
- Minority carriers gain enough energy to knock loose more electrons
- Leads to a chain reaction of carrier multiplication
๐ง Both mechanisms allow reverse current to flowโbut only after overcoming a critical voltage threshold.
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