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An alternative, which is used for voltage references that need to be highly stable over long periods of time, is to use a Zener diode with a temperature coefficient (TC) of +2 mV/°C (breakdown voltage 6.2–6.3 V) connected in series with a forward-biased silicon diode (or a transistor B-E junction) manufactured on the same chip. [4]
Severely overloaded Zener diodes in reverse bias shorting. A sufficiently high voltage causes avalanche breakdown of the Zener junction; that and a large current being passed through the diode causes extreme localised heating, melting the junction and metallisation and forming a silicon-aluminium alloy that shorts the terminals.
Internal resistance causes "leveling off" of a real diode's I–V curve at high forward bias. The Shockley equation doesn't model this, but adding a resistance in series will. The reverse breakdown region (particularly of interest for Zener diodes) is not modeled by the Shockley equation.
In electronics, the Zener effect (employed most notably in the appropriately named Zener diode) is a type of electrical breakdown, discovered by Clarence Melvin Zener. It occurs in a reverse biased p-n diode when the electric field enables tunneling of electrons from the valence to the conduction band of a semiconductor , leading to numerous ...
When the device is forward biased (connected with the p-side, having a higher electric potential than the n-side), this depletion region is diminished, allowing for significant conduction. Contrariwise, only a very small current can be achieved when the diode is reverse biased (connected with the n-side at lower electric potential than the p ...
If no diode is forward-biased then no diode will provide drive current for the output's load (such as a subsequent logic stage). So the output additionally requires a pull-up or pull-down resistor connected to a voltage source, so that the output can transition quickly [ a ] and provide a strong driving current when no diodes are forward-biased.
The saturation current (or scale current), more accurately the reverse saturation current, is the part of the reverse current in a semiconductor diode caused by diffusion of minority carriers from the neutral regions to the depletion region. This current is almost independent of the reverse voltage. [1]
These are diodes that conduct in the reverse direction when the reverse bias voltage exceeds the breakdown voltage. These are electrically very similar to Zener diodes (and are often mistakenly called Zener diodes), but break down by a different mechanism: the avalanche effect. This occurs when the reverse electric field applied across the p ...