"Semiconductor Nano-Conductor ON Time Can Be Increased" - Penn Scientists

“Unity is strength” this is not only a proverb but now a well established logic, which the Penn scientists are recently dealing with. The Penn researchers are trying to study the blinking phenomenon of nanorods of semiconductors which has remained as a puzzle for around a decade now. Even more, the scientists have proved that the time for which the nanorods shine, can be increased. The research was conducted by a team researchers including Marija Drndic, associate professor at Penn University, Catherine Crouch of Swarthmore College, Dmitry Novikov, school of medicine NY University and a group of students - graduate student Siying Wang and post doctorial fellows Claudia Querner and Tali Dadosh, all of the Dept of Physics and Astronomy, Penn’s school of Arts and sciences.

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Nanorods

The study was based on a peculiar property exhibited by Semiconductors. When these materials are reduced to a nanoscale, they are “blink” something like clicked ON and OFF continuously at irregular intervals. This is not something with which we observe in case of a Light emitting diode, commonly called as a LED. An LED on the contrary emits light (shines) continuously when exposed to tiniest bit of energy, may be electrical or chemical or heat. Semiconductors on the other hand, may have an ON/Off time which may range from microseconds to hours together. Drndic’s team wanted to increase the total ON time for these nanorods. After applying many different imaging techniques, researchers came to the conclusion of clustering semiconductor nanorods to increase their ON time significantly.

The conclusion was supported by an experiment conducted by the group. In that demonstration, the researchers deposited Cadmium Selenide nanorods on a substrate and projected a Blue laser on these semiconductors. A video taken of the phenomenon which was exhibited by the material helped to get the data about how long the ON time of nanorods could sustain itself. This was a joint exercise of all nanorods clustered together. The team now resorted to study the behavior of each nanorod separately under an electron microscope. Finally, the team could come up with a theory, though not exactly but over all root cause of the “blinking” effect is that one electron in a nanorod influence another in the adjacent nanorod.

The study by Penn researchers will prove to be advantageous for fluorescent labels used by Biologists. Though, the blinking is visible only under a microscope, it will be quite useful for Biologists. The study would help in increasing the ON time of these materials significantly, may be for a few minutes. Further research in this aspect would perhaps be aimed at studying such particle interactions using more ordered nanorod assemblies and controlled inter-particle separations. The current research is published in the Journal Nature Communications.

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