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2014年英语四级�力练习:慢速VOA(6.9)

  From VOA Learning English, this is the Technology Report.

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  It seems that electronic devices just keep getting smaller. Scientists in the United States have announced the creation of the first transistor with only two dimensions.

  A transistor is a small electronic device that transfers or carries electronic current. The device helps to create an electrical circuit that provides power to other devices. Scientists hope these new 2D transistors will be used for building high-resolution displays that need very little energy.

  Two groups of scientists created these 2D transistors. One group is at the Argonne National Laboratory outside of Chicago, the other group is at the University of California. They report that the transistors are only a few atoms thick, any layer of any material that thin may be considered two-dimensional.

  Usually transistors are made with the element silicon. But the scientists say they use materials that have even better electronic properties. Computer processors, memory chips, TV screens and other electronic devices contain billions of silicon-based transistors. But these very small electrical parts have certain limitations.

  Dimitris Ioannou is an electrical engineering professor at George Mason University. He says the traditional transistor has been improved as much as it can be. He adds that researchers have been looking for new materials with special features. He says researchers want transistors to be see through and soft.

  "If the layers are very thin the transistor can become flexible, so it doesn't have to be rigid, like it would be in a silicon chip. So people can think of applications like wearable electronics, like, you know, television screens and other things," said Ioannou.

  These new transistors can also carry higher current. They also can move the current much faster than traditional transistors. This is important for high-definition screens.

  Dimitris Ioannou says the scientific success could prove very useful in the future.

  "This is the first time every layer is a single [atom] layer, more or less, and that's the novelty of it. Now, how good and how useful it will be, it's still in research phase, but it certainly is an advance," said Ioannou.

  Scientists say there is no good method for printing a large number of these new transistors on one base material, but they believe that someday it may be possible.

  And that's the VOA Learning English Technology Report. For more technology stories, go to our website 51voa.com. Give us a like on the VOA Learning English Facebook page. Follow us on twitter at VOA Learning English. You can also watch videos on the VOA YouTube Channel. I'm Jonathan Evans.

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