Description:

One of the areas that is currently being most thoroughly researched with respect to future applications is the manipulation of surfaces on a nanometric scale, up to the point of practically constructing and manipulating structures atom by atom, and whereby the quantum effects could give these materials new properties, with revolutionary applications for nanoelectronics, optoelectronics and computing. One of these structures is the so-called quantum dot, in which electrons lose their capacity for mobility in spatial dimensions and become confined to a zero dimension (a dot). At the moment, the experiments with semiconductor materials most similar to quantum dots are the formation of nanoislands, semiconductor islands of several tens of nanometers of diameter and height. These islands can be produced using lithographic techniques, "printing" them onto the surface of a substrate, but for a decade now, scientists have been working on a new, and more efficient and stable, method for constructing them: the spontaneous formation of nanoislands.

A team of researchers has developed an unprecedented level of control of the distribution, shape and composition of the SiGe nanoislands, such that by varying the thickness of the layers of germanium and the temperature of the silicon substrate they can obtain, at will, large densities of small pyramid islets, large round islets distributed at much lower densities or even a uniform mixture of pyramid and rounded islands. As for the control of the composition of the islands SiGe semiconductor material, the researchers have observed that as temperature is increased, so does the silicon content, independently of the form and distribution of the nanoislands.
 

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