I don't think that SiC semiconductors are anything particularly new. And, according to
when applied to LEDs, SiC seminconductors are used to create blue LEDs. That yellow colored phosphor is what changes to light to white.
Here are the types of semicondictors used to create different colors, according to that URL:
"Silicon carbide (SiC),
indium gallium nitride (InGaN), and zinc selenide
(ZnSe) produce blue LED’s.
(GaP), and gallium nitride (GaN) produce green
"Gallium arsenide/phosphide (GaAsP) produce
red, orange and yellow LED’s.
arsenide (AlGaAs) produces red and infrared."
It goes on to say that white light can be made by combining red, green, and blue, although I'm pretty sure that's the more expensive way of making a white LED. The cheaper approach is just to use a blue plus a phosphor.
I think they do pay for themselves even at the current prices. I replaced 3 50W halogen bulbs on my kitchen hood with 8W LED lamps which are brighter which means I can operate them at a lower dimmer setting. Bulbs were $20 each.
savings per year at 5hrs a day for 360 days at 11c per kWh = $7. so return is in 3 years approx.
This is conservative since we now keeps the main kitchen lights off most of the time since all we need is lights over the stove at least in the daytime. Earlier, we had to turn all the lights on for an extra 65W for 5x13W CFLs.
Given the cost of the bulbs, the savings can accrue over time but with the limited lifetimes (power electronics typically) I am not sure the bulbs will ever pay for themselves based on electrical usage. I do know that in a number of applications they are very nice - quick to start and energy efficient (more for the PR and customer experience than real savings). Some companies will want to jump on the bandwagon just for the green-ness of the bulbs, again maybe more PR than anything else.