双层石墨烯物理属性好于单层
文章来源:未知 文章作者:enread 发布时间:2011-04-28 02:54 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

Researchers at the National Institute of Standards and Technology (NIST) have shown that the electronic properties of two layers of graphene(石墨烯) vary on the nanometer scale. The surprising new results reveal that not only does the difference in the strength of the electric charges between the two layers vary across the layers, but they also actually reverse in sign to create randomly1 distributed puddles3 of alternating positive and negative charges. Reported in Nature Physics, the new measurements bring graphene a step closer to being used in practical electronic devices. Graphene, a single layer of carbon atoms, is prized for its remarkable4 properties, not the least of which is the way it conducts electrons at high speed. However, the lack of what physicists5 call a band gap—an energetic threshold(门槛,极限) that makes it possible to turn a transistor6 on and off—makes graphene ill-suited for digital electronic applications.

Researchers have known that bilayer graphene, consisting of two stacked graphene layers, acts more like a semiconductor7 when immersed in an electric field.

According to NIST researcher Nikolai Zhitenev, the band gap may also form on its own due to variations in the sheets' electrical potential caused by interactions among the graphene electrons or with the substrate(基质) (usually a nonconducting, or insulating material) that the graphene is placed upon.

NIST fellow Joseph Stroscio says that their measurements indicate that interactions with the disordered insulating(绝缘的) substrate material causes pools of electrons and electron holes (basically, the absence of electrons) to form in the graphene layers. Both electron and hole "pools" are deeper on the bottom layer because it is closer to the substrate. This difference in "pool" depths, or charge density8, between the layers creates the random2 pattern of alternating charges and the spatially9(空间地) varying band gap.

Manipulating the purity of the substrate could give researchers a way to finely control graphene's band gap and may eventually lead to the fabrication of graphene-based transistors10 that can be turned on and off like a semiconductor.

Still, as shown in the group's previous work, while these substrate interactions open the door to graphene's use as a practical electronic material, they lower the window on speed. Electrons do not move as well through substrate-mounted bilayer graphene; however, this may likely be compensated11 for by engineering the graphene/substrate interactions.

Stroscio's team plans to explore further the role that substrates may play in the creation and control of band gaps in graphene by using different substrate materials. If the substrate interactions can be reduced far enough, says Stroscio, the exotic(异国的) quantum properties of bilayer graphene may be harnessed to create a new quantum field effect transistor.



点击收听单词发音收听单词发音  

1 randomly cktzBM     
adv.随便地,未加计划地
参考例句:
  • Within the hot gas chamber, molecules are moving randomly in all directions. 在灼热的气体燃烧室内,分子在各个方向上作无规运动。 来自辞典例句
  • Transformed cells are loosely attached, rounded and randomly oriented. 转化细胞则不大贴壁、圆缩并呈杂乱分布。 来自辞典例句
2 random HT9xd     
adj.随机的;任意的;n.偶然的(或随便的)行动
参考例句:
  • The list is arranged in a random order.名单排列不分先后。
  • On random inspection the meat was found to be bad.经抽查,发现肉变质了。
3 puddles 38bcfd2b26c90ae36551f1fa3e14c14c     
n.水坑, (尤指道路上的)雨水坑( puddle的名词复数 )
参考例句:
  • The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。
  • The road was filled with puddles from the rain. 雨后路面到处是一坑坑的积水。 来自《简明英汉词典》
4 remarkable 8Vbx6     
adj.显著的,异常的,非凡的,值得注意的
参考例句:
  • She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
  • These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。
5 physicists 18316b43c980524885c1a898ed1528b1     
物理学家( physicist的名词复数 )
参考例句:
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
6 transistor WnFwS     
n.晶体管,晶体管收音机
参考例句:
  • 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。
7 semiconductor Uzuwq     
n.半导体
参考例句:
  • 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。
8 density rOdzZ     
n.密集,密度,浓度
参考例句:
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
9 spatially ca2278711fa6d1d851ea605dea2e8224     
空间地,存在于空间地
参考例句:
  • A well-defined array of stable fringes results and the field is spatially coherent. 结果得到一组完全确定的稳定条纹,而光场是空间相干的。
  • The units are collaged together by a serial tectonic spatially and temporally. 这些构造单元是由构造原因,依一定的时空序列拼贴在一起的。
10 transistors ff750796e6ff1fb40d6a8248a6485dc3     
晶体管( transistor的名词复数 ); 晶体管收音机,半导体收音机
参考例句:
  • 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。
11 compensated 0b0382816fac7dbf94df37906582be8f     
补偿,报酬( compensate的过去式和过去分词 ); 给(某人)赔偿(或赔款)
参考例句:
  • The marvelous acting compensated for the play's weak script. 本剧的精彩表演弥补了剧本的不足。
  • I compensated his loss with money. 我赔偿他经济损失。
TAG标签: carbon layers graphene
发表评论
请自觉遵守互联网相关的政策法规,严禁发布色情、暴力、反动的言论。
评价:
表情:
验证码:点击我更换图片