Nano resistor: control of the content of oxygen atom

A new study in the journal of applied physics shows that the electronic properties of a new oxide thin layer of resistance can be regulated by controlling the content of oxygen atoms in the material.

Researchers at the London nanotechnology center in Washington, dc, on Dec. 9, 2014, created a new, small, high-resistance resistor for quantum circuits. This resistor drives the use of quantum devices in computing and basic physics research. The researchers described the thin-film resistors in an article in the journal of applied physics, published by the American physical association.

One of the applications of this resistor is that it can be used in quantum phase slip circuits (QPS). This circuit is a very narrow strips of superconducting material wire, superconducting wire that can use a kind of basic, counterintuitive quantum properties called quantum tunneling effect, make the magnetic flux moved back and forth in the superconducting wires and break through the barrier, it is not in our regular world of classical mechanics.

In 2006, the Dutch Kavli institute of nano science and technology of scientists proposed quantum phase slip circuit can be used to redefine "ampere" - a measure of current - by putting a QPS and linked to the basic features of the universe (rather than with the standard laboratory physical systems linked together). Other research groups have also proposed that QPS devices can be used as qubits for quantum computers - quantum bits are the basic unit of quantum information in such computers.

London component technology center for nano electronic characteristic experiment, the scientists said Paul Warburton resistor need to QPS device in fragile quantum state is unstable and isolated from the outside world full of noise. "In the application of the current standard, the resistor also ACTS as a stabilizing force for quantum devices." He added.

But the conventional materials that make the resistance in the integrated circuit generally cannot provide enough resistance to the QPS circuit in a very small form.

Warburton and his collaborators turned to the chromium oxide complex to produce high-resistance, compact nanoresistors. They used a technique called aerosol deposition to make chrome-oxide thin layers of resistance. By controlling the concentration of oxygen atoms in the thin layer, the researchers were able to adjust the resistance of the chromium oxide thin layer: the more components of oxygen atoms, the higher the resistance.

"Replacing chromic atoms with oxygen will affect the number of electrons that carry current and the way electrons jump through the material." "Warburton explained.

The researchers cooled the resistor at a temperature of 4.2 kelvin and measured its resistivity for materials with different oxygen and chromium atomic weights. Poor conductivity of materials, such as the researchers tested chrome oxide thin layer materials, at low temperature are generally have higher resistance, and QPS circuit required resistor is can work normally under the low temperature resistance, because only when the temperature is low enough, quantum effects would go beyond the classic effects become dominant. The researchers also measured high resistance to the high levels of oxygen atoms, which are compatible with most QPS circuits.

The team also described the contact resistance characteristics of the chromium oxide thin layer on the interface of niobium silicon. Making QPS circuits with niobium silicon nanowires is one way to measure the new quantum standard for amperes. The researchers found that adding a layer of gold between chromium oxide and niobium silicon could reduce contact resistance - a beneficial result. The researchers" next step is to incorporate their new resistors into QPS devices.