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Is this the work that launched a thousand publications? 
L. T. Canham Appl. Phys. Lett. 57, 1046 - 1048 (1990)

Canham's work on porous silicon has a title which gives no hint of the importance of this work. It is entitled: ``Silicon Quantum Wire Fabrication by Electrochemical and Chemical Dissolution of Wafers''. The work has three figures, the first one being a schematic cross-sectional view of silicon at various porosities. It is the remaining two figures which gripped the attention of a large number of physicists. They provided graphic illustration of efficient photoluminescence (PL) and its shift from the infra-red to red as the porosity of the sample increased. In his words, ``proof'' of quantum confinement.

Silicon is the workhorse of the semiconductor industry. But is exhibits no worthwhile luminescence. With Canham's discovery was born the optimism that electronics and optics could be integrated onto the same chip -- a holy grail of the semiconductor industry.

Porous silicon had been known for long ever since Uhlir's work in 1956. It had also been studied in detail in the 1980s by Beale et al. who proposed a model for its formation and by Gupta et al. who studied Si-H vibration properties. Surprisingly, workers prior to Canham missed seeing visible PL. The only earlier observation was by Furukawa and Miyasato (Phys. Rev. B 38 , 5726 (1988)) on Si nanoparticles who presented a photograph of bright red emission but did not publish any PL data.

In conclusion, Canham (i) demonstrated efficient visible PL in Si for the first time; (ii) proposed quantum confinement to explain this and (iii) showed that the fabrication process is simple and dirt cheap.

[P.S. Our title is taken from Alexander Pope's famous poem on Helen of Troy :``Is this the face that launched a thousand ships'']

1999-01-04