Recently, a joint team in China found polar rectification in Ti/Fatigued-SrTiO3 heterojunction and invented a new type of electronic components-"polarized diode" based on the effect.
From the perspective of movability, charges can be divided into two types: itinerant and localized.
For the electronic components with itinerant charges, there are two relationships between current (J) and voltage (V) under electric field. One type is the resistance element with symmetrical J-V curves and the other is the current diode with an asymmetrical J-V relationship (rectification effect) (as shown in Figure a and b below).
Current diodes are widely used in storage, computing, communication and other fields, and have become the most critical basic components in modern electronics. The situation is slightly different for electronic components that use localized charges as the carrier.
Components such as capacitors with symmetrical polarization (P) and voltage (V) relationships have been invented (Figure c below).
As for electronic components with asymmetrical P-V relationship (polar rectification effect), there has been no report so far. Therefore, if an asymmetric P-Vcurve can be found to form rectification effect of polarization, then a polarized diode can be made, which will have potential applications in rectifiers, storage, and computing.
Prof. SHENG Zhigao’s research team from the High Magnetic Field Laboratory, Hefei Institutes of Physical Science cooperated with researchers from the Institute of Physics of the Chinese Academy of Sciences and the Ningbo Institute of Materials of the Chinese Academy of Sciences introduced an appropriate amount of oxygen vacancies into the dielectric material SrTiO3 through electrical fatigued method.
These oxygen vacancies and the surrounding electrons form "polarons", and these "polarons" can form electric polarization (P) under the electric field.
Then, components with rectifying effect are constructed by preparing a heterojunction composed of metallic Ti and fatigued SrTiO3.
When a negative electric field (-V) applied to the component, the interface forms a very weak polarization P. and when a positive electric field (+V) applied to the component, the interface forms a very strong polarization P.
This asymmetrical P-V relationship indicates that the device has a polarized rectification effect and is a polarized diode, which may become the basic component of future electronic devices.
The results were published in ACS Applied Materials & Interfaces entitled “Polar Rectification Effect in Electro-Fatigued SrTiO3-Based Junctions” and applied for invention patent.
This work was supported by the National Key Research and Development Program, the National Natural Science Foundation, the Chinese Academy of Sciences' Frontier Science Key Research Project, and the High Magnetic Field Anhui Provincial Laboratory Fund.
Schematic images of J-V and P-V relationships for typical electronic devices.(a) J-Vcurveof resistive element; (b) J-Vcurve of current diode; (c) P-Vcurve of the capacitive element; (d) is a schematic diagram of the polarized diode and P-V relationship experimental data.
