Are White LEDs Converted to Ultraviolet LEDs by exposing them to radiation?

Question

Just Wondering What Effects Gamma Rays have on LED's

Answer 1

"Most "white" LEDs in production today are based on an InGaN-GaN structure, and emit blue light of wavelengths between 450 nm – 470 nm blue GaN. These GaN-based, InGaN-active-layer LEDs are covered by a yellowish phosphor coating usually made of cerium-doped yttrium aluminum garnet (Ce3+:YAG) crystals which have been powdered and bound in a type of viscous adhesive. The LED chip emits blue light, part of which is efficiently converted to a broad spectrum centered at about 580 nm (yellow) by the Ce3+:YAG. The single crystal form of Ce3+:YAG is actually considered a scintillator rather than a phosphor. Since yellow light stimulates the red and green receptors of the eye, the resulting mix of blue and yellow light gives the appearance of white, the resulting shade often called "lunar white". This approach was developed by Nichia and was used by them from 1996 for manufacturing of white LEDs."

White LEDs can also be made by coating near ultraviolet (NUV) emitting LEDs with a mixture of high efficiency europium based red and blue emitting phosphors plus green emitting copper and aluminum doped zinc sulfide (ZnS:Cu,Al). This is a method analogous to the way fluorescent lamps work. However the ultraviolet light causes photodegradation to the epoxy resin and many other materials used in LED packaging, causing manufacturing challenges and shorter lifetimes. This method is less efficient than the blue LED with YAG:Ce phosphor, as the Stokes shift is larger and more energy is therefore converted to heat, but yields light with better spectral characteristics, which render color better. Due to the higher radiative output of the ultraviolet LEDs than of the blue ones, both approaches offer comparable brightness.

The newest method used to produce white light LEDs uses no phosphors at all and is based on homoepitaxially grown zinc selenide (ZnSe) on a ZnSe substrate which simultaneously emits blue light from its active region and yellow light from the substrate.

A new technique just developed by Michael Bowers, a graduate student at Vanderbilt University in Nashville, involves coating a blue LED with quantum dots that glow white in response to the blue light from the LED. This technique produces a warm, yellowish-white light similar to that produced by incandescent bulbs."

From Wikipedia, the free, online encyclopedia at:
http://en.wikipedia.org/wiki/Led

Hope this helps!

Answer 2

No, a white LED actually is an Ultraviolet LED with a layer of phosphorescent material between the diode and the lit face of the device. The U/V light makes the phosphor glow just like the coating inside a fluorescent lamp.

Answer 3

I think that "white" LED's are really blue LED's that have been coated with phosphorescent translucent paint. The blue light gets absorbed (or some of it does) and then reemitted as white light. I don't know what exposing the LEDs to radiation will do.

Answer 4

You cannot change one type of LED to another by exposing it to radiation. You need to change the type of material in the LED to change the wavelength.