July 13, 2006 – Researchers at the U. of Toronto say they’ve created a “wet” semiconductor device that outperforms grown-crystal semiconductor devices by a factor of 10x in terms of light sensitivity.
The research team mixed the semiconductor nanoparticles in a flask containing extra-pure oleic acid, the main ingredient in olive oil. A drop of the solution is placed on a glass slide patterned with gold electrodes, and spin-coated out into a smooth, continuous film. After a two-hour bath in methanol, the solvent evaporates, leaving an 800nm-thick layer of light-sensitive nanoparticles.
Key to the process is keeping it controlled at the nanometer scale, tailoring colloidal nanocrystal size and surfaces, according to research study lead author Gerasimos Konstantatos, a doctoral researcher at U. of Toronto.
At room temperature, the photodetectors were about 10x more sensitive to infrared rays than sensors currently used in military night-vision and biomedical imaging. Potential applications include low-cost, high-performance designer semiconductors in short-wavelength infrared detectors and emitters.
The research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada through the Canada Foundation for Innovation; the Province of Ontario, through the Ontario Centers of Excellence; and the Canada Research Chairs program. Results were published in the July 13 issue of the journal Nature.