I was trying to make a cat’s whisker diode from a beautiful piece of silicon carbide I had laying in my crystal collection, but I noticed a faint glow. Probing further, I found that one of the largest crystals emitted quite a bit of light over an amazingly large area. Curious, I broke off that particular crystal and mounted it on a brass plate with JB Weld. I then soldered some safety pins in a way that they always touch just the right spots.

Below are two pictures of the device emitting light. One picture forward biased and one reverse. It emits light both ways!

What I have is a pair of schottky diodes in antiseries. Each metal-semiconductor contact forms a diode, which can point in either direction depending on whether the work function of the steel is greater or smaller than that of the SiC. In either case, when sufficient bias is applied one will enter reverse breakdown and the other will then be forward biased and conducting current. The forward biased one would then able to emit light.

Unlike most LEDs this one is by no means efficient. It draws 3A at 12v to emit a measly estimated .5mcd. Everything else turns to heat, VERY fast.

I have yet to measure the bandgap.