Some time ago, the publication Communications Physics published a scientific article "Harnessing ferroelectric domains for negative capacitance", the authors of which were Russian physicists from the Southern Federal University (Rostov-on-Don) Yuri Tikhonov and Anna Razumnaya, physicists from the French Jules Verne Picardy University Igor Lukyanchuk and Anais Sen, as well as materials scientist from the Argonne National Laboratory Valery Vinokur. The article tells about the creation of an "impossible" capacitor with a negative charge, which was predicted decades ago, but only now has been put into practice.
The development promises to revolutionize the electronic circuits of semiconductor devices. A pair of "negative" and a conventional positively charged capacitor, connected in series, raises the input voltage level at a given point above the nominal value to the level necessary for the operation of specific sections of electronic circuits. In other words, the processor can be powered by a relatively low voltage, but those sections of the circuits (blocks) that need an increased voltage value for operation will receive a controlled supply with an increased voltage using pairs of "negative" and conventional capacitors. This promises to improve the energy efficiency of computing circuits and more.
Prior to this implementation of negative capacitors, a similar effect was achieved for a short time and only under special conditions. Russian scientists, together with colleagues from the United States and France, have come up with a stable and simple negative capacitor structure suitable for mass production and for normal operation.
The structure of a negative capacitor developed by physicists consists of two separated regions, each of which contains nanoparticles of a ferroelectric with a charge of the same polarity (in the Soviet literature they were called ferroelectrics). In the normal state, ferroelectrics have a neutral charge, which occurs due to randomly oriented domains within the material. Scientists have managed to dissolve nanoparticles with the same charge in two separate physical regions of the capacitor - each in its own region.
A so-called domain wall, an area of polarity reversal, immediately appeared on the conditional border between two different polar regions. It turned out that the domain wall can be moved if voltage is applied to one of the regions of the structure. The displacement of the domain wall in one direction became equivalent to the accumulation of a negative charge. Moreover, the more the capacitor is charged, the lower the voltage across its plates. This is not the case with conventional capacitors. Increasing the charge leads to an increase in the voltage across the plates. Since the negative and ordinary capacitors are connected in series, the processes do not violate the law of conservation of energy, but lead to the appearance of an interesting phenomenon in the form of increasing the supply voltage at the necessary points of the electronic circuit. It is curious to see how these effects will be implemented in electronic circuits.
Author: Gennady Detinich
