Solid state lighting technologies use Light Emitting Diodes (LEDs). A diode is the simplest sort of semiconductor device. Broadly speaking, a semiconductor is a material with a varying ability to conduct electrical current.

Tiny, LEDs fabricated from layers of silicon and seeded with atoms of phosphorus, or germanium, arsenic and other rare-earth elements, exploit the quirky laws of quantum physics to transform electrons directly into photons of light, without heat. A cheap plastic reflector focuses the light into a conical beam that can be narrow and very bright, or wide and diffuse.

A diode restricts the flow of current to one direction: electricity enters from one side and exits out the other. In between, the current passes through a structure called a die. The die contains an area called the junction, where the actual light generation takes place. A contact in the center of the junction is attached to the incoming lead (the anode). As a current passes through the LED, the materials that make up the junction react, and light is emitted. By experimenting with different junction materials and package designs, LEDs are now bright enough to be considered for applications that traditionally use incandescent bulbs.

Technical advances have greatly improved the quality and reliability of LEDs since they were invented in the 1960s, making them much brighter and more efficient. The late 1990s brought high-brightness LEDs that could shine continuously for 100,000 hours, or 30 to 40 years in normal service. The first LEDs emitted light only at pure wavelengths or colours – blues, greens, yellows, oranges or reds – they were unsuitable for domestic lighting. The high-brightness white LED that emitts at all visible wavelengths to produce white light is a relatively new development.

The LUTW Luxeon lights can be utilized in a number of different applications and the most appropriate solution is dependent on the overall needs, budget and type of installation.The energy sources for LUTW's home lighting projects have included Person Powered Pedal Generators, Pico Hydro and Pico Wind Turbines and Solar Photovoltaic.

Light Comparison Table

- LEDs are made from layers of different semi-conductor material formed on a sapphire substrate, one on top of the other using a process called Epitaxial crystal growth

- About 13,000 LEDs can be formed on the substrate which can be about .25 x.25 units in size

- Tiny gold contacts are applied to each chip site

- Each individual chip is packaged to form a lighting device