文章来源:未知 文章作者:meng 发布时间:2010-10-27 01:35 字体: [ ]  进入论坛

Researchers at Rensselaer Polytechnic1 Institute developed a new method for using water to tune2 the band gap of the nanomaterial graphene(石墨烯) , opening the door to new graphene-based transistors4 and nanoelectronics. By exposing a graphene film to humidity, Rensselaer Professor Nikhil Koratkar and his research team were able to create a band gap in graphene – a critical prerequisite(先决条件) to creating graphene transistors. At the heart of modern electronics, transistors are devices that can be switched "on" or "off" to alter an electrical signal. Computer microprocessors6 are comprised of millions of transistors made from the semiconducting material silicon7, for which the industry is actively8 seeking a successor.

Graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chain-link fence, has no band gap. Koratkar's team demonstrated how to open a band gap in graphene based on the amount of water they adsorbed to one side of the material, precisely9 tuning10 the band gap to any value from 0 to 0.2 electron volts11. This effect was fully12 reversible(可逆的) and the band gap reduced back to zero under vacuum. The technique does not involve any complicated engineering or modification13 of the graphene, but requires an enclosure where humidity can be precisely controlled.

"Graphene is prized for its unique and attractive mechanical properties. But if you were to build a transistor3 using graphene, it simply wouldn't work as graphene acts like a semi-metal and has zero band gap," said Koratkar, a professor in the Department of Mechanical, Aerospace14, and Nuclear Engineering at Rensselaer. "In this study, we demonstrated a relatively15 easy method for giving graphene a band gap. This could open the door to using graphene for a new generation of transistors, diodes(二极管) , nanoelectronics, nanophotonics, and other applications."

Results of the study were detailed16 in the paper "Tunable17 Band gap in Graphene by the Controlled Adsorbtion of Water Molecules18," published this week by the journal Small. See the full paper at: http://dx.doi.org/10.1002/smll.201001384

In its natural state, graphene has a peculiar19(特殊的,奇怪的) structure but no band gap. It behaves as a metal and is known as a good conductor. This is compared to rubber or most plastics, which are insulators21(绝缘体) and do not conduct electricity. Insulators have a large band gap – an energy gap between the valence(原子价) and conduction bands – which prevents electrons from conducting freely in the material.

Between the two are semiconductors23, which can function as both a conductor and an insulator20. Semiconductors have a narrow band gap, and application of an electric field can provoke(驱使,激怒) electrons to jump across the gap. The ability to quickly switch between the two states – "on" and "off" – is why semiconductors are so valuable in microelectronics.

"At the heart of any semiconductor22 device is a material with a band gap," Koratkar said. "If you look at the chips and microprocessors in today's cell phones, mobile devices, and computers, each contains a multitude of transistors made from semiconductors with band gaps. Graphene is a zero band gap material, which limits its utility. So it is critical to develop methods to induce a band gap in graphene to make it a relevant semiconducting material."

The symmetry(对称,整齐) of graphene's lattice(晶格) structure has been identified as a reason for the material's lack of band gap. Koratkar explored the idea of breaking this symmetry by binding24 molecules to only one side of the graphene. To do this, he fabricated graphene on a surface of silicon and silicon dioxide, and then exposed the graphene to an environmental chamber25 with controlled humidity. In the chamber, water molecules adsorbed to the exposed side of the graphene, but not on the side facing the silicon dioxide. With the symmetry broken, the band gap of graphene did, indeed, open up, Koratkar said. Also contributing to the effect is the moisture interacting with defects in the silicon dioxide substrate(基质) .

"Others have shown how to create a band gap in graphene by adsorbing different gasses to its surface, but this is the first time it has been done with water," he said. "The advantage of water adsorption, compared to gasses, is that it is inexpensive, nontoxic, and much easier to control in a chip application. For example, with advances in micro-packaging technologies it is relatively straightforward26(简单的,坦率的) to construct a small enclosure(附件,围墙) around certain parts or the entirety of a computer chip in which it would be quite easy to control the level of humidity."

Based on the humidity level in the enclosure, chip makers27 could reversibly tune the band gap of graphene to any value from 0 to 0.2 electron volts, Korarkar said.


1 polytechnic g1vzw     
  • She was trained as a teacher at Manchester Polytechnic.她在曼彻斯特工艺专科学校就读,准备毕业后做老师。
  • When he was 17,Einstein entered the Polytechnic Zurich,Switzerland,where he studied mathematics and physics.17岁时,爱因斯坦进入了瑞士苏黎士的专科学院,学习数学和物理学。
2 tune NmnwW     
  • He'd written a tune,and played it to us on the piano.他写了一段曲子,并在钢琴上弹给我们听。
  • The boy beat out a tune on a tin can.那男孩在易拉罐上敲出一首曲子。
3 transistor WnFwS     
  • This make of transistor radio is small and beautifully designed.这半导体收音机小巧玲珑。
  • Every transistor has at least three electrodes.每个晶体管至少有三个电极。
4 transistors ff750796e6ff1fb40d6a8248a6485dc3     
晶体管( transistor的名词复数 ); 晶体管收音机,半导体收音机
  • In semiconductor receivers transistors take the place of vacuum tubes. 在半导体收音机中晶体管代替了真空管。
  • We often turn to this handbook for information on transistors. 我们常从这本手册查阅有关晶体管的资料。
5 prerequisite yQCxu     
  • Stability and unity are a prerequisite to the four modernizations.安定团结是实现四个现代化的前提。
  • It is a prerequisite of entry to the profession that you pass the exams.做这一行的先决条件是要通过了有关的考试。
6 microprocessors 937cb6d36748cbbe6ff19e715f8bfcc4     
微(信息)处理机( microprocessor的名词复数 )
  • This sort of work would have been inconceivable before the advent of microprocessors. 在微处理机问世之前这种工作是难以想象的。
  • In microprocessors, the name used for the IEEE interface bus standard. 微处理机中,IEEE接口总线标准的名字。
7 silicon dykwJ     
  • This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
  • A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。
8 actively lzezni     
  • During this period all the students were actively participating.在这节课中所有的学生都积极参加。
  • We are actively intervening to settle a quarrel.我们正在积极调解争执。
9 precisely zlWzUb     
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
10 tuning 8700ed4820c703ee62c092f05901ecfc     
n.调谐,调整,调音v.调音( tune的现在分词 );调整;(给收音机、电视等)调谐;使协调
  • They are tuning up a plane on the flight line. 他们正在机场的飞机跑道上调试一架飞机。 来自《简明英汉词典》
  • The orchestra are tuning up. 管弦乐队在定弦。 来自《现代汉英综合大词典》
11 volts 98e8d837b26722c4cf6887fd4ebf60e8     
n.(电压单位)伏特( volt的名词复数 )
  • The floating potential, Vf is usually only a few volts below ground. 浮置电势Vf通常只低于接地电位几伏。 来自辞典例句
  • If gamma particles are present, potential differences of several thousand volts can be generated. 如果存在γ粒子,可能产生几千伏的电位差。 来自辞典例句
12 fully Gfuzd     
  • The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气,然后全部呼出。
  • They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
13 modification tEZxm     
  • The law,in its present form,is unjust;it needs modification.现行的法律是不公正的,它需要修改。
  • The design requires considerable modification.这个设计需要作大的修改。
14 aerospace CK2yf     
  • The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
  • Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。
15 relatively bkqzS3     
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
16 detailed xuNzms     
  • He had made a detailed study of the terrain.他对地形作了缜密的研究。
  • A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
17 tunable e846714832475261a7cdb5d8f2d1c687     
  • Researchers realised that a tunable laser beam might be useful in surgery. 研究人员意识到,可调谐激光束也许可以用在外科手术中。 来自辞典例句
  • The experiment of wavelength conversion using tunable external-cavity semiconductor laser is performed. 利用可调谐外腔半导体激光器进行了波长转换实验。 来自互联网
18 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
19 peculiar cinyo     
  • He walks in a peculiar fashion.他走路的样子很奇特。
  • He looked at me with a very peculiar expression.他用一种很奇怪的表情看着我。
20 insulator b50xs     
  • Few substances can equal fur as an insulator.作为绝缘体很少有其他材料能与动物皮毛相媲美。
  • A loose mulch acts on the surface as an insulator.疏松的覆盖物在土壤表面起了隔热的作用。
21 insulators c88ab4337e644aa48cdb61df6ccc0271     
绝缘、隔热或隔音等的物质或装置( insulator的名词复数 )
  • There is no sharp line separating conductors from insulators. 实际上并没有一个明显的界限将半导体和绝缘体分开。
  • To reduce heat losses the pipes are covered by thermal insulators. 为了减少热散失,管子外包保温层。
22 semiconductor Uzuwq     
  • In the beginning,engineers hoped to use semiconductor lasers.在开始时,工程师们希望能够利用半导体激光器。
  • The main agent of the company brand semiconductor sales.本公司主要代理各品牌半导体销售。
23 semiconductors 0e1983fea761e849266037e7a40cb125     
n.半导体( semiconductor的名词复数 )
  • Crystals may be insulators, semiconductors, or conductors. 晶体可以是绝缘体,半导体,或导体。 来自辞典例句
  • Semiconductors containing such impurities are called p-type semiconductors. 含有这类杂质的半导体叫做P型半导体。 来自辞典例句
24 binding 2yEzWb     
  • The contract was not signed and has no binding force. 合同没有签署因而没有约束力。
  • Both sides have agreed that the arbitration will be binding. 双方都赞同仲裁具有约束力。
25 chamber wnky9     
  • For many,the dentist's surgery remains a torture chamber.对许多人来说,牙医的治疗室一直是间受刑室。
  • The chamber was ablaze with light.会议厅里灯火辉煌。
26 straightforward fFfyA     
  • A straightforward talk is better than a flowery speech.巧言不如直说。
  • I must insist on your giving me a straightforward answer.我一定要你给我一个直截了当的回答。
27 makers 22a4efff03ac42c1785d09a48313d352     
  • The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
  • The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》
TAG标签: water research graphene