17 July 2012
Elad Mentovich, a Ph.D. student at Tel Aviv University, has made a vertical transistor based on a single carbon-60 molecule that he reckons could be the basis for both a logic transistor and a memory element.
Major companies in the memory industry have already expressed interest in the technology, said Mentovich, who was awarded a prize for his work at May’s European conference of the Materials Research Society. He co-authored a paper with Bogdan Belgorodsky, Itsik Kalifa and Shachar Richter that was presented there.
Because the memory is a based on a single molecule of carbon in a spherical form it can be as small as one-nanometer in diameter, making it a candidate for post-CMOS integration. The molecular memory is ready to produced in existing wafer fabs Mentovich asserts.
The properties of the molecular quantum dot system are investigated using a vertical structure. The molecular transistor can be operated in a voltage-controlled switching mode and in a gate-controlled hysteresis mode, suitable for memory. It is not clear from abstracts whether Mentovich has obtained non-volatile operation, but as a replacement for DRAM the memory has the advantage of small size and not requiring a separate capacitor.
A polaron-based model is used to explain the operation of the transistor and to introduce some general rules for the construction of polaronic molecular transistors. A polaron is a slow moving electron that carries with it a region of crystal dislocation thereby combining electron and a cloud of phonons.
Mentovich and Richter published a paper in Applied Physics Letters in July 2011 entitled: Post-complementary metal-oxide-semiconductor vertical and molecular transistors: A platform for molecular electronics. This asserted that C60-based carbon as a transistor channel could demonstrate higher currents and lower leakage than non-molecular versions.