Yes. https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Does a wide bandgap JFET glow under forward bias?
Started by ●September 15, 2020
Reply by ●September 15, 20202020-09-15
On Tuesday, September 15, 2020 at 1:27:45 PM UTC-7, Tim Williams wrote:> Yes. > https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138Maybe. A SiC item is not just 'wide bandgap', but DIRECT bandgap in nature; there's no highspeed way for multistep recombination to far outpace the one-step-light-emitting that causes the blue glow.
Reply by ●September 17, 20202020-09-17
On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" <tiwill@seventransistorlabs.com> wrote:>Yes. >https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 > >TimI recall pictures of bipolar transistors emitting weak white light. Pease?
Reply by ●September 17, 20202020-09-17
On 2020-09-17 13:35, John Larkin wrote:> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" > <tiwill@seventransistorlabs.com> wrote: > >> Yes. >> https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 >> >> Tim > > I recall pictures of bipolar transistors emitting weak white light. > Pease? >CMOS does it too--google mcmanus "picosecond imaging circuit analysis" Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●September 17, 20202020-09-17
torsdag den 17. september 2020 kl. 19.35.47 UTC+2 skrev John Larkin:> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" > <tiwill@seventransistorlabs.com> wrote: > > >Yes. > >https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 > > > >Tim > > I recall pictures of bipolar transistors emitting weak white light. > Pease?with enough power most components do ;)
Reply by ●September 17, 20202020-09-17
On Thursday, September 17, 2020 at 10:35:47 AM UTC-7, John Larkin wrote:> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" > <tiw...@seventransistorlabs.com> wrote: > > >Yes. > >https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 > > > >Tim > > I recall pictures of bipolar transistors emitting weak white light.Pictures, but perhaps taken with an IR camera? There's a good quantum-mechanics reason to expect that a silicon charge-carrier-injection across the bandgap does not make white light, but (of course) an IR camera that picks up light is capable of visible-light in white or false color as a readout option. Pictures of emssion is possible. White emission is not.
Reply by ●September 17, 20202020-09-17
On Thu, 17 Sep 2020 13:09:20 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote:>On Thursday, September 17, 2020 at 10:35:47 AM UTC-7, John Larkin wrote: >> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" >> <tiw...@seventransistorlabs.com> wrote: >> >> >Yes. >> >https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 >> > >> >Tim >> >> I recall pictures of bipolar transistors emitting weak white light. > >Pictures, but perhaps taken with an IR camera? There's a good quantum-mechanics reason to >expect that a silicon charge-carrier-injection across the bandgap does not make white >light, but (of course) an IR camera that picks up light is capable of visible-light in white >or false color as a readout option. > >Pictures of emssion is possible. White emission is not.Of course it is. https://www.semitracks.com/reference-material/failure-and-yield-analysis/failure-analysis-die-level/light-emission.php Reverse biased pn junctions represent a different situation. When a small reverse bias is applied to a junction, the depletion region widens, causing low current but a substantial electric field. As the reverse bias is increased, the probability that a highly excited electron will cross the junction increases. This will generate photons from the recombination of carriers whose energies can be significantly above the bandgap energy. The resulting emission spectrum will have a significant tail which can extend into the visible wavelengths.
Reply by ●September 17, 20202020-09-17
On 2020-09-17 22:09, whit3rd wrote:> On Thursday, September 17, 2020 at 10:35:47 AM UTC-7, John Larkin wrote: >> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" >> <tiw...@seventransistorlabs.com> wrote: >> >>> Yes. >>> https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 >>> >>> Tim >> >> I recall pictures of bipolar transistors emitting weak white light. > > Pictures, but perhaps taken with an IR camera? There's a good quantum-mechanics reason to > expect that a silicon charge-carrier-injection across the bandgap does not make white > light, but (of course) an IR camera that picks up light is capable of visible-light in white > or false color as a readout option. > > Pictures of emssion is possible. White emission is not. >The light was emitted by an EB junction in reverse breakdown. Many years ago, after reading Pease's piece on the subject, I opened up a transistor in a TO-18 can to take a look. The light was whitish. That surprised me. I expected monochromatic light. Jeroen Belleman
Reply by ●September 17, 20202020-09-17
On Thu, 17 Sep 2020 22:33:45 +0200, Jeroen Belleman <jeroen@nospam.please> wrote:>On 2020-09-17 22:09, whit3rd wrote: >> On Thursday, September 17, 2020 at 10:35:47 AM UTC-7, John Larkin wrote: >>> On Tue, 15 Sep 2020 15:27:38 -0500, "Tim Williams" >>> <tiw...@seventransistorlabs.com> wrote: >>> >>>> Yes. >>>> https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 >>>> >>>> Tim >>> >>> I recall pictures of bipolar transistors emitting weak white light. >> >> Pictures, but perhaps taken with an IR camera? There's a good quantum-mechanics reason to >> expect that a silicon charge-carrier-injection across the bandgap does not make white >> light, but (of course) an IR camera that picks up light is capable of visible-light in white >> or false color as a readout option. >> >> Pictures of emssion is possible. White emission is not. >> > >The light was emitted by an EB junction in reverse breakdown. >Many years ago, after reading Pease's piece on the subject, I >opened up a transistor in a TO-18 can to take a look. The light >was whitish. That surprised me. I expected monochromatic light. > >Jeroen BellemanWith tens or hundreds of volts c-e, I'd expect a normally biased transistor to emit some visible light. Zeners, too.
Reply by ●September 17, 20202020-09-17
Tim Williams wrote:> Yes.Nuts do it as well, so why shouldn't a JFET? https://i.imgur.com/WxqQIEB.jpg > https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3234138/#msg3234138 Both effects could probably be combined in a fancy way. Best regards, Piotr
