????合成薄膜石墨烯所需要的成本和時(shí)間要顯著高于生產(chǎn)屑狀石墨烯。后者通常是通過(guò)一個(gè)“又快又臟”的程序，把塊狀石墨分解成幾百萬(wàn)個(gè)小片，而大片的石墨烯薄膜則是小心地“種”在銅、鍺或金剛砂材質(zhì)的基板上。

????薄膜狀石墨烯的產(chǎn)量也非常有限。默騰斯說(shuō)：“現(xiàn)在有幾千家小公司都可以生產(chǎn)石墨烯，但是價(jià)格非常昂貴，而且產(chǎn)量很低。”他還指出，一片直徑1英寸的石墨烯圓片的價(jià)格就高達(dá)100美元左右。

????卡耐基梅隆大學(xué)（ Carnegie Mellon University）電子與計(jì)算機(jī)工程學(xué)教授伊萊亞斯?托維指出，用石墨烯生產(chǎn)晶體管的另一個(gè)障礙是，石墨烯不具備所謂的“帶隙”。這是一種非常重要的性能，它使晶體管能夠“開(kāi)”和“關(guān)”，而且在“關(guān)”的狀態(tài)下不會(huì)泄漏電荷。

????珍妮?劉也說(shuō)：“帶隙工藝一直是阻礙用石墨烯研制晶體管和電腦芯片的最大挑戰(zhàn)?！?/p>

????帕特森稱：要克服帶隙問(wèn)題，就要求對(duì)這種材料的控制必須達(dá)到原子層面，而“這可以說(shuō)是在推動(dòng)現(xiàn)有技術(shù)的邊緣。10年內(nèi)，我們將看到這些問(wèn)題逐步得到解決?！?/p>

很大程度上只是時(shí)間問(wèn)題

????托維指出，如果石墨烯要想成為硅的補(bǔ)充產(chǎn)品，它的成功將取決于成本和性能。

????“硅的基礎(chǔ)生產(chǎn)工藝是建立在幾十億美元的投資基礎(chǔ)上的，因此很難被完全取代。石墨烯要想取代硅，不僅要具備卓越的性能，還要具備極低的價(jià)格，才能促使整個(gè)行業(yè)改變方向?！?/p>

????硅用于生產(chǎn)晶體管的歷史可以追溯到上世紀(jì)50年代，相比之下，石墨烯只有10年的歷史，但是石墨烯已經(jīng)取得了顯著的進(jìn)步。比如8年前，最大的石墨烯薄膜還是在實(shí)驗(yàn)室中用手工做出來(lái)的，寬度還比不上人類的一根頭發(fā)絲。而誠(chéng)如珍妮?劉所言：“現(xiàn)在，新型的卷對(duì)卷印刷工藝使100米長(zhǎng)的石墨烯薄膜已經(jīng)成為現(xiàn)實(shí)?！?/p>

????珍妮?劉補(bǔ)充說(shuō)：“隨著行業(yè)對(duì)石墨烯技術(shù)的興趣、投資和研究力度日益加大，我認(rèn)為石墨烯行業(yè)形成規(guī)模經(jīng)濟(jì)，生產(chǎn)出真正低成本、量產(chǎn)級(jí)的高質(zhì)量石墨烯只是一個(gè)時(shí)間問(wèn)題?！?/p>

????曼徹斯特大學(xué)的維加亞拉哈萬(wàn)說(shuō)：“石墨烯的其它障礙可以用時(shí)間和努力來(lái)克服。我們每天都在學(xué)習(xí)新東西，目前我們還有很多不懂的東西，而且還有很多研究要做。”比如研究人員現(xiàn)在才剛剛開(kāi)始研究石墨烯對(duì)環(huán)境的污染后果以及對(duì)人體健康的影響。

????但是，石墨烯或許足以顛覆市值達(dá)2萬(wàn)億美元的電子行業(yè)，這個(gè)前景仍然不容忽視。

????比如帕特森就暢想道：“我們不妨想象一下，一枚只有普通郵票十分之一大小的芯片，醫(yī)生卻可以用它來(lái)檢測(cè)各種東西。到時(shí)候，大家不用每次都抽三管血來(lái)檢查兩個(gè)指標(biāo)，然后第二天再來(lái)取結(jié)果。而是只需要一滴血，就可以檢測(cè)幾百種指標(biāo)，然后馬上獲得結(jié)果。石墨烯可以讓這種想法成為現(xiàn)實(shí)?！保ㄘ?cái)富中文網(wǎng)）

????譯者：樸成奎

????Synthesizing graphene in sheet form is considerably more expensive and time-consuming than producing graphene flakes. Whereas the latter typically involves a "quick and dirty" process by which bulk graphite is disassembled into millions of tiny pieces, Lau explained, large sheets of graphene are carefully "grown" on substrates such as copper, germanium, or silicon carbide.

????Graphene sheets are also prone to defects and "very difficult to make in good quality," Ron Mertens, owner and editor of Graphene-Info.com, said.

????Production capacity is also very limited. "There are thousands of small companies that can make graphene, but it's expensive and low-capacity," Mertens said. A round wafer measuring one inch in diameter, for instance, costs about $100, he added.

????An even thornier obstacle on the way to graphene transistors is the fact that the material has no "band gap," an essential property that allows transistors to be turned on and off without leaking electronic charge in the "off" state, said Elias Towe, a professor of electrical and computer engineering at Carnegie Mellon University.

????"Band-gap engineering has been and remains the biggest challenge in the development of graphene transistors and computer chips," Lau said.

????It requires controlling the material almost down at the atomic level, and "that's really pushing the edges of existing technology," Patterson said. "In 10 years, we'll start to see these problems be solved."

'It is largely a matter of time'

????If graphene is to succeed as a replacement for silicon, every unit of cost and performance will make a difference, Towe said.

????"Silicon is hard to displace, with all the billions dollars of investments made in manufacturing infrastructure," he said. "A replacement for silicon has to offer extraordinary performance at extremely rock-bottom cost to compel industry to change its way."

????Though graphene is just 10 years old -- in contrast, use of silicon in transistors dates to the early 1950s -- considerable progress has already been made. For example, the largest graphene sheet was produced by hand in a laboratory eight years ago; its width was less than that of a human hair. "Nowadays, roll-to-roll printing of graphene sheets up to 100 meters long has been achieved," Lau said.

????"With the increasing interest, investment, and research in graphene-based technology, I think it is largely a matter of time before the economy of scale kicks in and truly low-cost, large-scale production of high-quality graphene is accomplished," she added.

????The next series of hurdles "can be overcome with time and effort," said Vijayaraghavan of the University of Manchester. "We're learning new things every day. There is still much we don't understand, and still plenty of research to be done." For example, researchers have only just begun to study the consequences of graphene pollution on the environment and human health.

????Still, the possibilities that graphene holds for the nearly $2 trillion global electronics industry are difficult to ignore.

????"Imagine a tiny chip, one-tenth the size of a postage stamp, that your doctor could use to test for all kinds of things," Patterson said. "You'd walk in, and instead of having to give three vials of blood to test for two things and then get the results the next day, your doctor could use one drop of blood to test for hundreds of things and you'd get the results right away. Graphene makes it possible."