New method for grow­ing graphene could fi­nally let us build some­thing with it

Tehran Times - - SCIENCE -

Graphene is an amaz­ing ma­te­rial with an equally an­noy­ing set of con­straints that make it ex­tremely dif­fi­cult to work with. One of the most sig­nif­i­cant prob­lems we’ve had with adapt­ing the ma­te­rial for com­mer­cial use is pro­duc­ing it.

While a num­ber of meth­ods of graphene pro­duc­tion have been demon­strated, none of them have lent them­selves to the kind of mas­sive scale that typ­i­fies the sil­i­con in­dus­try’s abil­ity to man­u­fac­ture, well, sil­i­con. In early 2016, the en­tire foundry in­dus­try was es­ti­mated to be ca­pa­ble of nearly 12 mil­lion wafer starts per month (in 200mm-equiv­a­lent wafers).

Graphene doesn’t have to scale all the way up to that level be­fore en­ter­ing pro­duc­tion, but any wide­spread adop­tion of the ma­te­rial re­quires it to achieve its own econ­omy of scale. New re­search from Rice Univer­sity and the Oak Ridge Na­tional Lab­o­ra­tory may have moved us closer to that idea, with a new method of cre­at­ing a large con­tin­u­ous roll of graphene.

Chem­i­cal va­por

The re­searchers at ORNL used a chem­i­cal va­por de­po­si­tion (CVD) process to man­u­fac­ture graphene, which is some­thing we’ve been do­ing for quite awhile al­ready, but with a new twist.

Much like tra­di­tional CVD ap­proaches to pro­duce graphene, the re­searchers sprayed a gaseous mix­ture of hy­dro­car­bon pre­cur­sor mol­e­cules onto a metal­lic, poly­crys­talline foil. How­ever, they care­fully con­trolled the lo­cal de­po­si­tion of the hy­dro­car­bon mol­e­cules, bring­ing them di­rectly to the edge of the emerg­ing graphene film. As the sub­strate moved un­der­neath, the car­bon atoms con­tin­u­ously as­sem­bled as a sin­gle crys­tal of graphene up to a foot in length.

By run­ning the process at a high tem­per­a­ture and care­fully mon­i­tor­ing the gas mix­ture con­cen­tra­tion, the team was able to keep the growth oc­cur­ring where they wanted it to. Yield­ing a sin­gle crys­tal sheet struc­ture, as op­posed to clus­ters of the ma­te­rial, also cre­ates a more uni­form and larger con­tin­u­ous sheet of ma­te­rial.

A novel method

A re­search team de­vel­oped a novel method that pro­duces large, mono­layer sin­gle-crys­tal-like graphene films more than a foot long.

Large sin­gle crys­tals are more me­chan­i­cally ro­bust, and may even have higher con­duc­tiv­ity, ORNL lead coau­thor Ivan Vlas­siouk told Phys.Org. “[It’s] be­cause weak­nesses aris­ing from in­ter­con­nec­tions be­tween in­di­vid­ual do­mains in poly­crys­talline graphene are elim­i­nated,” he said.

As for what this could mean for semi­con­duc­tor and other ap­pli­ca­tions of graphene, it could rep­re­sent a gen­uine break­through … given suf­fi­cient time.

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