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Sunday, January 4, 2015

#316 “1.24” is a number to remember

Yes, learning should be based primarily on understanding rather than memorization and semiconductor science and engineering is no exception in this regard.


 Still, there are things worth memorizing.  Here is an example concerned with a simple relation converting wavelength of light to energy and vice versa. It comes very handy when interactions of light with semiconductors (absorption, emission, etc.) are of interest.


 It starts with the titans of solid state physics, Max Planck and Albert Einstein and their formulation of a simple relation linking energy E and frequency ν of light E = h ν  where h is a Planck constant. It is enough to recall now that the frequency  ν = c/λ where c is a speed of light in vacuum and  λ the light’s wavelength or the length of the wave of light. So, E (eV)= h c/ λ and with h and c being constants we end up with a convenient formula E (eV)= 1.24/ λ (μm) used to convert wavelength of light to energy and vice versa. Actually, with E~1/λ relation being rather obvious, what needs to be remembered is a proportionality factor 1.24.


Posted by Jerzy Ruzyllo at 08:42 AM | 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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