New radiation resistant materials would help crafts on long space missions

Washington, June 11 : Researchers at Northwestern University in the US have developed new transistors that hold up well when exposed to radiation, which could prove helpful on long space missions.

These transistors, that have been based on a new kind of material, have already been lifted into outer space on the space shuttle Endeavour and attached to the outside of the International Space Station for radiation testing.

The transistors, which used a new kind of gate dielectric material called a self-assembled nanodielectric (SAND), were placed on the space station during a spacewalk on March 22 this year.

The transistors will remain there for a year as part of a NASA materials experiment to see how they and other materials hold up to the harsh space environment.

SANDs were developed at Northwestern by the research group of Tobin Marks, Vladimir N. Ipatieff Research Professor of Chemistry in the Weinberg College of Arts and Sciences and Professor of Materials Science and Engineering in the McCormick School of Engineering and Applied Science.

According to Marks, in addition to possibly proving handy in space, SANDs could help pave the way for a variety of new technologies, including printable and transparent electronics.

Transistors, the devices used to amplify or switch signals that are the building blocks of all modern electronic devices, generally consist of a substrate, gate and semiconductor.

In between the gate and semiconductor lies the dielectric, which acts as an insulator to prevent short-circuiting while stabilizing charged current carriers in the nearby semiconductor.

While silicon dioxide has historically been the dominant dielectric material for silicon-based electronics, Marks and his research group have been trying to create next-generation semiconductor and dielectric materials with properties that silicon and silicon dioxide can't provide - such as transparency, printability and physical flexibility.

The dielectric material would need to be thin, be a good insulator and be able to stabilize the charges moving through the semiconductor by having what is called a high dielectric constant, which is the relative ability of the material to store an electric charge for a given applied field strength.

What resulted were SANDs, which Marks and his team created through a dipping process that creates self-assembled molecular thin films.

Not only do SANDs meet all the requirements for next-generation dielectrics, but they were also found to be resistant to radiation, which could be ideal for spacecrafts on long space trips.

Marks and his team hope to have an even better idea of how the SAND transistors fare after they remain on the space station for a year.

ANI