Insulator-Metal Transition In Thermal Imagers

Researchers have discovered what makes vanadium dioxide films conduct electricity (insulator-metal transition). Their findings will enable thermal imaging devices with a sensitivity and reaction rate superior to those of the currently existing analogs.

While 100-nanometer thin films of vanadium dioxide (VO2) do not normally conduct electricity, their resistance drops up to 100,000 times when slightly heated. This may happen under applied voltage, for example. That property is used to create high-speed switchable devices and sensors for direct current or alternating signal in the terahertz, microwave, optical, or infrared range.

Materials scientists found VO2 films could become conductive in the mid-20th century. Until now, the precise mechanism behind the change in the material’s electrical properties was unknown. Being aware of that mechanism (insulator-metal transition) enables application-oriented materials design. That includes the synthesis of thin films with predefined properties, such as the temperature at which conductivity changes or the ratio between the resistances before and after heating.

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