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Sunday, October 26, 2014

#310 Recombination means light

The recombination is a physical effect occurring only in semiconductors. It refers to the effect in which electrons from the upper energy band recombine with the holes in the lower energy band and release energy in the process. If a given semiconductor features a direct energy gap then the energy is released mostly as an electromagnetic radiation in the form of a visible light from red to blue range, or invisible infrared light. The operation of all Light Emitting Diodes (LEDs), so ubiquitous these days, is based entirely on this simple principle (strictly speaking the processes leading to the emissive recombination in organic semiconductors are somewhat different than in their inorganic counterparts, but the general idea remains thesame and either way recombination rules… 


I don’t think we fully recognize how profound is our dependence on the process of recombination in semiconductors, so effectively exploited in LEDs. On top on displays, etc., think of LEDs as a source of light in currently virtually all lighting applications.  With life expectancy of just a few month of continuous use and efficiency of about ridiculously low 10%, incandescent bulbs are essentially gone and will never be back. Fluorescent bulbs, including compact fluorescent, are performing better, but will gradually follow incandescent bulbs on the way out as neither in terms of efficiency nor the lifetime they are able to compete with LED-based bulbs.


To make a long story short, whenever and wherever you will see an artificial light, think semiconductors and think recombination.


Posted by Jerzy Ruzyllo at 02:44 PM | Semiconductors | Link is the personal blog of Jerzy Ruzyllo. With over 35 years of experience in academic research and teaching in the area of semiconductor engineering (currently holding position of a Distinguished Professor of Electrical Engineering and Professor of Materials Science and Engineering at Penn State University), he has a unique perspective on the developments in this progress driving technical domain and enjoys blogging about it.

With over 2000 terms defined and explained, Semiconductor Glossary is the most complete reference in the field of semiconductors on the market today.

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