First Light-Emitting Transistor

The inventor of the LED makes another optoelectronics breakthrough

3 min read

21 January 2004--When IEEE Medal of Honor winner Nick Holonyak Jr. invented the light-emitting diode in the early 1960s, it would have been difficult to guess that the device would become a mainstay of a global optoelectronics industry worth billions of dollars. Now almost 40 years later, Holonyak and his colleagues Milton Feng and Walid Hafez at the University of Illinois, Urbana-Champaign, have developed a light-emitting transistor or LET, a device that could have an equally profound impact.

A light-emitting diode is essentially a junction between a region of p-doped semiconductors having an excess of holes and an n-doped region having an excess of electrons. At the junction between the two regions, the electrons and holes can combine. Because electrons occupy a higher conduction band than holes, they have more energy, which must be released during the process of recombination.

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

1 min read
A chart showing the timeline of when a transistor was invented and when it was commercialized.

Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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