Canadian researchers at McGill University (Montréal, Québec) have achieved engineering control of the piezoelectric effect in quantum dots. From the news release,
The generation of an electric field by the compression and expansion of solid materials is known as the piezoelectric effect, and it has a wide range of applications ranging from everyday items such as watches, motion sensors and precise positioning systems. Researchers at McGill University’s Department of Chemistry have now discovered how to control this effect in nanoscale semiconductors called “quantum dots,” enabling the development of incredibly tiny new products.
Although the word “quantum” is used in everyday language to connote something very large, it actually means the smallest amount by which certain physical quantities can change. A quantum dot has a diameter of only 10 to 50 atoms, or less than 10 nanometres. By comparison, the diameter of the DNA double-helix is 2 nanometres. The McGill researchers have discovered a way to make individual charges reside on the surface of the dot, which produces a large electric field within the dot. This electric field produces enormous piezoelectric forces causing large and rapid expansion and contraction of the dots within a trillionth of a second. Most importantly, the team is able to control the size of this vibration.
Cadmium Selenide quantum dots can be used in a wide range of technological applications. Solar power is one area that has been explored, but this new discovery has paved way for other nanoscale device applications for these dots. This discovery offers a way of controlling the speed and switching time of nanoelectronic devices, and possibly even developing nanoscale power supplies, whereby a small compression would produce a large voltage.
The research was published in Nano Letters (behind a paywall).