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February 11, 2010

Single Step doping of Graphene

Applied Physics Letters - Single step, complementary doping of graphene

A single-step doping method capable of high resolution n- and p-type doping of large area graphene is presented. Thin films of hydrogen silsesquoxane on exfoliated graphene are used to demonstrate both electron and hole doping through control of the polymer cross-linking process. This dual-doping is attributed to the mismatch in bond strength of the Si–H and Si–O bonds in the film as well as out-gassing of hydrogen with increasing cross-linking. A high-resolution graphene p-n junction is demonstrated using this method

If this technique works for graphene (graphene with a lot of hydrogen) then other researchers have computed that p-dooped graphane would superconduct at 90 kelvin

So the combined work could accelerate graphene displacing silicon for electronics and computers and for a possibly superior superconducting material to be developed. The superconducting material (p-doped graphane) could also make vastly superior electronics.

Eurakalert has the press release

By applying a commercially-available spin-on-glass (SOG) material to graphene and then exposing it to electron-beam radiation, researchers at the Georgia Institute of Technology created both types of doping by simply varying the exposure time. Higher levels of e-beam energy produced p-type areas, while lower levels produced n-type areas.

For doping bulk areas such as interconnects that do not require patterning, the researchers simply coat the area with HSQ and expose it to a plasma source. The technique can make the nanoribbons up to 10 times more conductive than untreated graphene.



The technique was used to fabricate high-resolution p-n junctions. When properly passivated, the doping created by the SOG is expected to remain indefinitely in the graphene sheets studied by the researchers.

"This is an enabling step toward making possible complementary metal oxide graphene transistors," said Raghunath Murali, a senior research engineer in Georgia Tech's Nanotechnology Research Center.




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