Talk:Avalanche breakdown

Stub or not?

Not sure if this counts as a stub or not, it's my first shot at writing this, and some of the higher math and diagrams are missing, but it's a lot bigger than most stubs I've read. Comments/suggestions anyone? Astaroth5 14:13, 11 November 2005 (UTC).

I don't know what the page looked like when ou read it, but it consisted of two sentences and a link to Zener diode before I edited it just now.Envergure (talk) 13:08, 29 January 2010 (UTC)

Question

Is it the case that when material is destroyed by electrical current, avalanche breakdown is usually the process by which the destreuction occours. Ie: it's not just a thing that can happen, it's the thing that usually happens when you "fry" something?

No. There are many electrical processes that could damage a material. Avalanche breakdown is a specific process that involves impact ionization due to high electric fields. Despite the name, avalanche breakdown is not necessarily destructive and is actually used in some devices to provide builtin current amplification (like the avalanche photodiode). -- mattb @ 2006-09-14T14:56Z

There is nothing inherently harmful about avalanche breakdown. Provided that the maximum current and power dissipation of the device are not exceeded, it can be operated in that region indefinitely with no harmful effects. Devices are destroyed by excessive power dissipation as well as hot spots that occur due to current crowding. For any device, there is always a safe current level which will not cause damage; however, this limit is generally much lower than the maximum forward current. —Preceding unsigned comment added by 76.218.99.61 (talk) 04:29, 28 February 2011 (UTC)

Electron avalanche

Is this the same thing as electron avalanche? Propaniac (talk)

Pretty much, but "avalanche breakdown" specifically refers to an electron avalanche at a reverse-biased PN junction. An ideal PN junction only conducts in one direction, but real ones will "break down" and conduct the other way if the voltage is strong enough.Envergure (talk) 13:08, 29 January 2010 (UTC)

Zener breakdown

The explanation about zener breakdown seems a bit fuzzy...--90.184.74.236 (talk) 17:40, 1 September 2012 (UTC)

hysteresis

The statement that avalanche breakdown is hysteretic seems very strange to me. The avalanche multiplication factor typically depends only on external conditions and not on time, so the breakdown should be extinguished essentially immediately once multiplication is reduced. If there were hysteresis of the sort described, then one should be able to build a slow oscillator by feeding in an appropriate constant current -- enough to initiate breakdown but too low to sustain breakdown -- with a capacitance in parallel with the avalanche region. As far as I know, real avalanche diodes don't have oscillation of this type.

Aha, to answer my own question I see that for some avalanche diodes (i.e. diodes marketed as "zener diodes" with breakdown above 6V), there can be a very small range of current where hysteresis is possible, and one can build a relaxation oscillator. Here is a link to an old newsgroup discussion on this topic (sci.electronics.design, post by Winfield Hill on 8/5/97), with a bunch of links to academic references from the 1950s. --Nanite (talk) 14:46, 13 September 2013 (UTC)

I don't know if the transistor and diodes effects are related, but the Esaki oscillator may only work due to a hysteresis effect. --Mortense (talk) 21:40, 11 February 2018 (UTC)

@Nanite I also felt this strained the conventional usage of hysteresis - as it pertains to electrical science. After reviewing the accepted definition of "hysteresis", I for one am satisfied with the usage. Your answer is way better though.

Also, your write up above is fantastic. Very cool link as well. Thanks for that! 2600:6C44:667F:662E:1C2B:F64B:D570:8AE4 (talk) 08:55, 2 November 2022 (UTC)

What's "dubious" about basic electronics?

Tube diodes, gas tube diodes existed prior. Unless there was ions existant before voltage applied, a higher voltage is required to initiate conduction between two electrodes and, unless current is limited to microamperes, the voltage drops to a few volts along the conducting path. A 1960s transistor selection guide, I think TI, had avalanche transistor voltage drop after avalanche lower, and use of that "negative resistance" for oscillator use. You may be confused as SCR and TRIAC circuits use DIAC device for triggering. These DIAC also drop in voltage after triggering. Typically a NPN or NPNP device, though PN avalanche diodes qu TaylorLeem (talk) 03:53, 27 June 2020 (UTC)

The avalanche transistors operated as "programmable" avalanch diode like the gate programs a Programmable Unijunction Transistor, an NPNP device. TaylorLeem (talk) 03:58, 27 June 2020 (UTC)

Missing and misinformed sections?

Forgot to mention that hole plus electron recombination always generates a photon (even if you don't see it). And heat. Solar panels are PN junctions and should be mentioned. All junctions respond to light (photons), or why my one diode radio didn't work in bright sunshine. Not only electricity generated from light, but Thermoelectric semiconductors can gen power from heat but also provide refrigeration when reverse biased (heat is moved from one side of junction to the other). The Depletion Zone in PN junctions should have ref or detail. Specifically diodes used as Varactors or Voltage Variable Capacitors. (Varators are used in microwave amplifiers where standard semiconductors fail due to noise or frequency.) The high capacitance at low V can cause circuit design problems. Power diodes have a Recovery Time needed to reverse the charge carriers of which capacitance is part of. That "step recovery" has been used as frequency multiplier at high frequencies. In addition to Max reverse voltage, we should mention I(peak) vs I(ave). Many ots leds will Lase at high peak currents (keeping I(ave) low) however the diode specs degrade if above Manufacturers peak current spec. Mentioning Laser Diode thresholds as a confirmation of avalanche effects existing. Big subject! In addition to PN junction might mention PIN diodes with "undoped" layer in between. Not really a separate subject since the width and doping (see tunnel diode wiki) of the junction itself is what separates different diode characteristics. TaylorLeem (talk) 04:51, 27 June 2020 (UTC)

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