Semiconductors and the Information Revolution

CHAPTER 7. Light-Emitting Diodes

White Light for Green Consumers

One of the most exciting properties of semiconductors is their ability to convert electrical energy into light without the intermediary of heat. For thousands of years mankind had to be content with obtaining artificial light as a by-product of heat. Whether it was the warm glow of the camp fire, the deliberate burning of animal fat or vegetable oil, the nineteenth century sophistication of gas lighting or finally the amazing convenience of the electric filament lamp, light appeared as an indirect result of making something hot, and the colour of the light depended on the temperature achieved. (The reader may remember that in Chapter 1 we discussed briefly the concept of a spread ...