For further development of semiconductors and other future applications, it is said to be essential to characterise them in operation, but present techniques have been restricted to measurements of the electric field at a semiconductor's surface.
The technique exploits the response of an artificially introduced single electron spin to variations in its surrounding electric field, and enabled the researchers to study a semiconductor diode subject to bias voltages of up to 150V.
The team applied its method to diamond, a wide-band-gap semiconductor in which the electric fields can become very strong – a property important for low loss electronic applications.
According to the team, diamond has the advantage that it easily accommodates nitrogen-vacancy (NV) centres, a type of point defect that arises when two neighbouring carbon atoms are replaced by a nitrogen atom in the lattice.
The researchers first fabricated a diamond diode embedded with NV centres. They then localised a NV centre and recorded its optically detected magnetic resonance (ODMR) spectrum for increasing bias voltages.
From these spectra, values for the electric field could be obtained using theoretical formulas. The experimental values were then compared with numerical results obtained with a device simulator and found to be in good agreement – confirming the potential of NV centres as local electric-field sensors.
The researchers claim that electric-field sensing is not only relevant for electronic devices, but also for electrochemical applications.
In addition, the team notes its approach need not be restricted to NV centres in diamond: similar single-electron-spin structures exist in other semiconductors, like silicon carbide.
