LED or light-emitting diode flashlights are getting more and more popular these days. One of the main reasons is because the bulbs practically never burn out and they consumer very small amounts of power! LEDs are also being used as the backlight for laptop computers. Researchers at Purdue University have been pursuing a cheaper silicon-based LED instead of the expensive sapphire-based LED. In the new silicon-based LED research, the Purdue engineers "metallized" the silicon substrate with a built-in reflective layer of zirconium nitride. Silicon dissipates heat better than sapphire, so it is less likely to cause heat damage. Source: Purdue University.