Jul
27
Since the transistor replaced the vacuum tube about sixty years ago an ever-growing avalanche of electronics has enriched lives. While the thought about one’s power blocks and power supplies doesn’t seem like much in a home, everyone plus the support in businesses, governments and the data centers of the internet and cloud sum up to huge amount of energy.
Come up with a lot better transistor and the energy use demand could very well go down and more electronics could become available and battery life extended. The savings could be quite significant.
Researchers at the RIKEN Advanced Science Institute have created the world’s first transistor that uses the electrostatic accumulation of electrical charge on the surface of a strongly correlated material to trigger bulk switching of the electronic state. This new technology is already functional at room temperature and triggered by a potential of only 1 volt. The switching mechanism provides a novel building block for ultra low power devices, non-volatile memory and optical switches based on a new device concept.
RIKEN Electrostatic Transistor. Click image for the largest view.
The transistor, based on quantum mechanics, has been shrinking in size for many decades. But, conventional electronics is approaching quantum-scaling limits, motivating the search for alternative technologies to take its place. Among these, strongly correlated materials, whose electrons interact with each other to produce unusual and often useful properties, have attracted growing attention. One of these properties is triggered in phase transitions: applying a small external voltage can induce a very large change in electric resistance, a mechanism akin to a switch that has many potential applications.
The RIKEN team, led by Professor Yoshihiro Iwasa in their paper published in Nature explains the device uses an electric-double layer to tune the charge density on the surface of vanadium dioxide (VO2), a well-known classical strongly correlated material. Thanks to the strong correlation of electrons and electron-lattice coupling in VO2, this surface charge in turn drives localized electrons within the bulk to delocalize, greatly magnifying the change of electronic phase.
The team prepared metal–insulator–semiconductor field-effect transistors based on vanadium dioxide – a strongly correlated material with a thermally driven, first-order metal–insulator transition well above room temperature – and found that electrostatic charging at a surface drives all the previously localized charge carriers in the bulk material into motion, leading to the emergence of a three-dimensional metallic ground state. This non-local switching of the electronic state is achieved by applying a voltage of only about one volt.
The prime point is in voltage-sweep measurement, the first-order nature of the metal–insulator transition provides a non-volatile memory effect, which is operable at room temperature. No deep cooling required. They can show 1 volt potential is enough to switch the material from an insulator to a metal and trigger an astounding thousand-fold drop in resistance.
The electronic phase, however, is not the only thing that changes in this insulator-to-metal transition. Using synchrotron radiation from RIKEN’s Spring-8 facility in Harima, the research team analyzed the crystal structure of the VO2, showing that it, too, undergoes a transformation, from monoclinic to tetragonal structure. Electric-field induced bulk transformation of this kind is impossible using conventional semiconductor-based electronics and suggests a wide range of potential applications.
Should all of this lab work find its way, and the demand is certainly there, the team’s new switching mechanism takes this first discovery to a new level, demonstrating that a very small electric potential is enough to control macroscopic electronic states and offering a new route to controlling the state of matter.
One does wonder, as it’s outside of your humble writers competency realm, if this new technology would have a worthwhile effect on the quantum computer effort. If it does –
Oh. My. . .
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