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Physics · Ch 9 — Semiconductor Electronics

Zener Diode

9.3.6

Zener Diode

A Zener diode is a heavily doped silicon diode, named after its inventor C. Zener, specifically designed to be operated in the (otherwise destructive) reverse breakdown region -- its doping level can be tuned to give breakdown voltages ranging from as low as 2 V to over 1000 V. Physically it looks like an ordinary p-n junction diode except that its cathode lead is shaped to approximate the letter 'Z'; its circuit symbol keeps the usual diode arrowhead-and-bar shape but bends the bar into a small 'z' kink to …

Figure 9.19Zener diode: commercial appearance and circuit symbol

What this figure shows. Panel (a) is a photograph-style drawing of a real Zener diode component, a small cylindrical body with two wire leads, its cathode end identified by a black ring painted around the body. Panel (b) is its circuit symbol: the ordinary diode arrowhead-and-bar, but with the flat cathode bar bent at both corners into a small step shape reminiscent of the letter 'Z' -- the visual cue that immediately distinguishes a Zener diode symbol from an ordinary diode symbol …