my recent articles |
| Two-colour LED could lead to better screens |
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25 May 2007, for New Scientist A silicon light-emitting diode (LED) that can quickly switch between producing red and blue light could ultimately lead to smaller pixels for high-resolution displays. LEDs can normally only emit light of one colour. A new study shows that adding a certain rare earth metals can allow them to switch between two colours. The new LED is made from a layer of semiconducting silicon and a layer of insulating silicon dioxide. This creates a 100-nanometre-thick barrier that obstructs the flow of electrons. Europium, a rare earth metal, is then implanted within the silicon dioxide. Applying a voltage across the silicon dioxide barrier allows the electrons to cross the barrier - a quantum mechanical process known as "tunnelling." While tunnelling through the silicon, the electrons sometimes smack into the europium atoms, which sends them to a higher energy state. When these atoms fall back to their original state, they emit light. Read the rest of the story on the New Scientist website. |