LEDs and hot electrons

[c1ue]

Clue, I really hate doing this to you. But you keep insisting that you know about things you don't, and appealing to the authority of your experience to overwhelm perfectly reasonable concerns and corrections:

Sorry, you can flaunt all you want, but I both have direct experience working with silicon semiconductors (i.e. digital design) and work directly with individuals who design the machines that create gallium arsenide chips.

At the very least, you are significantly over-representing your expertise in this field (GaN LEDs), in which you consistently demonstrate such a profound lack of understanding.

All is clear now. You seem to think that my comments are directly exclusively to GaN LEDs, when all I'm noting is that there are shared physics based constraints between LEDs and semiconductors. And to be specific, semiconductors used for analog and digital design.

Yet I have specifically noted that there are fundamental differences between designs intended to perform analog/digital calculations vs. designs intended to generate light:

This is different than standard semiconductors where electrons are primarily used as electrical current.

Sure, LEDs do also use electrons to generate electrical current, but this is secondary to what they are intended to do: generate light.

So, to return to the question:

Are hot electrons only what you describe:

A hot electron is just one that has high momentum (is traveling rapidly in the semiconductor).

The answer is NO. For a physicist, this would be true, but in real life the cause and the effect are related.

A physicist might say that a car driving off a cliff is one event, and the car landing on someone underneath is a separate one, but engineers understand that one doesn't occur without the other.

I received my B.S. in Engineering Physics from UC Berkeley, and my Ph.D. in Electrical Engineering from the UC Santa Barbara, which was then, as it is now, ranked the #1 school in the world in the fields of optoelectronic semiconductor materials, and GaN in particular. I held 1 full academic scholarship as an undergraduate, and 2 fellowships as a graduate student. My work at UCSB resulted in numerous conference presentations, as well as authorships and co-authorships on 10 peer-reviewed archival journal articles, all involving the material system GaN, that is the subject of the paper you cited. One of my papers was co-authored with James Speck, the UCSB professor interviewed in the article you posted, in which he describes his own recent publication on Auger recombination.

I have designed and created gallium nitride LEDs (with my own hands) in lab, growing the material epitaxially using MOCVD, processing it in a cleanroom, testing it using a very wide range of characterization tools, analyzing the results, and publishing these. I have also worked on teams that made and published results from quite a few other GaN-based devices, some of which had never before been created by anyone, anywhere in the world. Other teams I worked on had, at the time, world-record performance. I have even (alone) created for the first time a new class of optoelectronic GaN devices, never constructed before my work, which was enabled by my work, spawning research efforts at other universities that sought to extend it. I invented and patented some of the new tools that allowed me to do this. One of these patents has been licensed by a major player in the LED industry.

This is all fine and interesting, but I fail to see how your LED expertise leads you to be able to categorize all hot electrons.

If you're trying to say that hot electrons in GaN LEDs are fundamentally different than in silicon or GaAs semiconductors - I'd be happy to say that you should know GaN LEDs better.

I, however, have worked for years on hot electron (as well as other related) fields in both silicon and GaAs designs, so know your comments are not correct for all instances. Equally, to be sure, I checked with several of my friends who create the machines which in turn create both GaN and GaAs products. They also have fancy schmancy degrees and what not, but more importantly design, field, and maintain the multi-million dollar machinery which has to do the industrial work of producing LEDs, solar panels, and what not. They too have dozens of patents. They validated what I said: hot electrons for high voltage designs primarily affect performance - to be specific they trigger discharges earlier than expected. Given that there are probably charge pumps and what not involved in building up voltages, I can see how this would affect LED overall output. However, hot electrons for smaller/lower voltage devices primarily affect behavior through structural damage exactly as I noted above.

But ultimately the issue is: you think you know all there is to know about hot electrons.

You don't.

If you said you know everything there is to know about hot electrons in GaN LEDs, then I would bow to that - although I don't how much you necessarily know about hot electrons in the non-light generating aspect of the LED (i.e. the control and setup circuitry).