Scientists have developed a technique that allows nanometer-sized particles to be positioned with very high precision on a surface, such as that of a silicon chip of the type used in computers, without damaging or contaminating it.
The new technique is the work of a team made up of, among others, Farnaz Niroui and Weikun “Spencer” Zhu, from the Massachusetts Institute of Technology (MIT) in the United States.
The technique, which combines chemistry, directed assembly processes and conventional manufacturing techniques, makes it possible to provide special qualities, achievable only through the use of nanoparticles, to devices such as chips, sensors, lasers and LEDs with great efficiency. Thanks to the extra qualities, the performance of such devices can be noticeably increased.
Transistors and other components of microelectronics are usually made by removing excess material from raw blocks until the desired arrangement of structures is achieved. But creating the smaller structures, which can enable higher performance and new functionality, requires expensive equipment and remains difficult.
A more precise way to create those components is to add material until you get the desired structure in the desired location. To do this, chemistry can be used to “grow” nanoparticles in a solution, drop that solution onto a template, arrange the nanoparticles, and then transfer them to a surface. However, this technique also involves great challenges. First, thousands of nanoparticles have to be placed on the template efficiently. And transferring them to a surface often requires a chemical glue, high pressure, or high temperatures, which could damage the surfaces and the resulting device.
Farnaz Niroui (right) and Spencer Zhu, in their MIT lab. (Photo: M. Scott Brauer. )
Niroui and his colleagues have come up with a new strategy to overcome these limitations. They have learned to use the powerful forces that operate at the nanometer scale to efficiently organize nanoparticles into a desired pattern and then transfer them to a surface without using chemicals or high pressures, and at lower temperatures than traditional methods. Since the surface material remains pristine, these nano-sized structures can be incorporated into components of electronic and even optical devices, where even tiny imperfections can degrade performance. (Font: NCYT by Amazings)