If you know much about LED lights then you know that they are typically built upon an n-type substrate. On the surface of the device, the electrode is attached to the p-type layer. Often, commercial LED lights also include some kind of substrate of sapphire. A scientist in LED research must always remember that when the refractive index of materials is not properly paired with the index of the semiconductor there is a chance of increased heat and, of course, potential danger. This is actually the exact opposite of one of the major benefits of LED lighting, that being that they do not retain or give off heat despite the generation of light. However, any potential dangers can be remedied simply by assuring that the basic scientific functions are executed properly in the design of each LED unit.
There have been many developments, experiments, and research done on the production and benefits of LED lighting. The semiconductor – device sends charges of incoherent narrow – spectrum light. LED lighting therefore emits a particular form of electroluminescence that can, theoretically, be easily utilized an alternative light source. The semiconducting chip of an LED light is of course, cased in solid plastic in the form of a lens – a very effective and very strong. Making LED lighting one of the safest kinds of bulb – lighting.
The development of LED began with the introduction of lighting devices and with gallium arsenide – particularly for infrared and red lighting purposes. Of course, LED lighting had a great beginning, already useful for things such as Christmas trees and theatrical lighting (being that they can be used in several colors.) However, the research and development of LED lighting has since grown and will continue to grow.
More advanced and especially more complex LED’s are those being created in ultraviolet, blue and even white shades. For example: an ultraviolet GaN LED,Blue type of LED uses a wide band gap semiconductor in GaN as well as InGaN (indium gallium nitrate). The concept was there, however, it was not until 1993 that high brightness of blue LED lighting was possible thanks to the work of a man named Shuji Nakamura from the Nicha Corporation.
White LED lights can be created in more than one way. For example: As I mentioned, most LED white lights are based on InGaN and GaN structural designs. These lights are said to be capable of emitting bluish light wavelengths between 450 nm and 470 nm blue from the GaN.
The GaN/InGaN lights usually use a yellowish colored phosphor coating of cerium – doped yttrium aluminum garnet (Ce3+:YAG). The Ce3+YAG crystals are considered a scintillator as opposed to a phosphor. Because yellow light acts to stimulate the red and green light receptors of someone’s eye, the appearance of white actually comes from the presence of the mix of the yellow and blue. The white light resulting from this is a shade of white often referred to as “lunar white” by people in and outside of the industry.
The overall spectrum of a white LED light will distinctly show that it comes directly from a GaN-based LED and can peak at about 465 nanometers. When more broad – strokes of shifted light emitted by the elements of Ce3+YAG phosphor the light emitted can be extended to between 500 and 700 nanometers. In manufacturing, the LED’s must be properly sorted during the process by their own particular characteristics because of the spectral characteristics of the diode.
White LED’s can be made in other ways as well, for example: one can coat near ultraviolet rays (NUV) that emit LED’s with a mix of highly efficient europium – based reds and blues, these phosphors added to green emitted by copper and aluminum doped zinc sulfide, or ZnS:Cu, Al. However, this method is less efficient than LED with YAG:Ce phosphor, primarily because it is larger and more energy is transformed into heat than with other LED’s.
A man named Micheal Bowers, as a graduate student in Nashville, TN at Vanderbilt University recently developed a kind of LED lighting that involves coating a blue LED with quantum dots. The quantum dots, in response to the LED light, will glow white. The effect is quite similar to incandescent bulbs – meaning that the technique produces a warm, glowing, yellowish light.
Before Bowers made his discovery, another of the most recent method of producing white – light LED’s is a method which makes use of absolutely no phosphors whatsoever. Some call the idea revolutionary – it is certainly a great idea in the development of LED’s today. The newest method is based on a homoepitaxially developed form of zinc selenide (ZnSe). Basically, the ZnSe substrate for this purpose is a creation which emits blue light simultaneously from the active region as well as the yellow from the substrate.