Termed quantum capacitance, this extra capacitance arises because the electron density is too low to shield the external electric field, as happens in a normal metallic conductor. Given the extra capacitance, the Y branches themselves take on a role as gates, with the depleted branch setting up an extra field that— counterintuitively—adds to the electric field of the external gates, explains Worschech.
How exactly this added capacitance between the Y branches is created is not yet completely understood. “There is a lot of new physics involved,” said Worschech. “This quantum capacitance becomes very efficient if you fine-tune the geometry and the voltages,” he adds.
The group has already started creating circuits using these Y-branch switches. One is a Schmitt trigger in which they reported a gain of 100. Replacing GaAs with silicon will allow them to reduce the size of these Y- branches, which may then become competitive with present-day transistors, Worschech predicts.
Peter Hadley of the Delft University of Technology (Netherlands) draws attention to two serious problems. The device’s high output impedance and near-absolute-zero operating temperature will block its general application in electronics, he believes.
The group reports, however, that it already has had some success creating circuits with Y- branches operating at room temperature.
Comprehension check
Say whether the following statements are true or false:
1. Downsizing transistor reaches a limit because quantum effects start interfering with their operation.
2. The German team has devised a device that could replace transistors in some situations.
3. The team reported that its Y- branch can’t amplify changes in voltage.
4. If a bias voltage is applied over Y’s stem and the extremities of its two branches, electrons travel up the stem and enter one branch.
5. Usually, downsizing field-effect transistors don’t run into problems.
6. The group has already had some success creating circuits with Y-branches.
Read the article again and answer the following questions:
1. What has opened the possibility of creating active electronic components smaller than present-day transistors?
2. Why does downsizing transistors reach a limit?
3. What does the device consist of?
4. How did the researchers create a Y-branch?
5. Where do electrons flow in the contact area?
6. What happens when a voltage is applied over the two terminals?
7. Does downsizing field–effect transistors run into any problems? What are they?
8. Why does termed quantum capacitance arise?
9. Did the group create anything using these Y-branch switches?
Make up your own vocabulary on this article.
Use the words you have chosen from this article in the sentences of your own.
CONTENTS
SECTION I
Unit 1. Biodegradable mems…………………………………………………3
Unit 2. No mirrors, no problem………………………………………………5
Unit 3. Beyond the speed of light…………………………………………….7
Unit 4. Superconducting gains……………………………………………….9
Unit 5. Nothing goes faster than light………………………………………11
Unit 6. Noise controls chaos………………………………………………..12
Unit 7. Ethics in space moves up the agenda……………………………….14
Unit 8. Protons singled out……………………………………………….…16
Unit 9. Neutrons caught in a trap…………………………………………...18
Unit 10. Silicon germanium makes its mark…………………………………20
Unit 11. Electricity warehouse will shift the balance of power……………...23
Unit 12. Physicists must lead on energy………………………………….….25
SECTION II
Unit 1. Magnetism under the microscope……………………………….….28
Unit 2. Colloids reinforce glass theory……………………………………...31
Unit 3. Quotable quotes……………………………………………………..35
Unit 4. Software pirates, avaunt…………………………………………….37
Unit 5. Cutting the cost of optical components……………………………..40
Unit 6. German team creates new type of transistor-like device…………...42
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