Photoluminescence in Porous Silicon

Leigh T. Canham
Chief Scientific Officer, pSiMedica Ltd., Malvern, and Honorary Professor, School of Physics and Astronomy, University of Birmingham, Birmingham, England, UK

Canham is suggested as a possible Nobel Prize winner “for the discovery of photoluminescence in porous silicon”

Porous silicon was accidentally discovered by Arthur Uhlic at Bell Laboratories in 1956. He was trying to fabricate silicon wafers for use in microelectronics, and he found experimentally this form of nanocrystalline silicon that is populated with holes. This did not suit his quest for highly polished wafers, so the material was forgotten until the late 1980s, when Leigh T. Canham reasoned that silicon quantum wires made of silicon might exhibit quantum confinement effects. In 1990 his short paper in Applied Physics Letters, “Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers,” astonished solid state physicists with its announcement of the demonstration of efficient visible light production by porous silicon. This paper is the most highly cited on the topic porous silicon, with 6,100 citations to date. That’s because research into porous silicon has concentrated on observations of and explanations for both photoluminescence and electroluminescence from this material, as well as its potential optoelectronic applications. In their 1997 review paper for Journal of Applied Physics, titled “The structural and luminescence of porous silicon,” Canham and his associates A.G. Cullis and P.D.J. Calcott pointed to three intriguing facts. Bulk silicon is simply incapable of emitting light, and yet with porosity it shines. Second, the light emitting nanostructure is easy to make within minutes. And third, silicon is the most important element for technology because of its dominance of microelectronics. This paper has recorded over 1,600 citations. The importance of the discovery of efficient luminescence from porous silicon is signaled by the very high levels of citations because they are indicative of the massive amount of research that has been devoted to this promising material.

Commentary on the Physics Laureates by Simon Mitton, Physics correspondent, ScienceWatch