experimental values were then compared with numerical |
semiconductors have many applications, including lightresults |
obtained with a device simulator and found to be in |
emitting diodes, transducers, alternative-energy devices |
good agreement-- confirming the potential of NV centers |
and high-power components. For further development of |
as local electric-field sensors. |
these and other future applications, it is essential to be |
Iwasaki and colleagues explain that the experimentally |
able to characterize wide-band-gap devices in operation. |
determined value for the electric field around a given NV |
The technique proposed by Iwasaki and colleagues for |
center is essentially the field ' s component perpendicular to |
measuring the electric field generated in a wide-band-gap |
the direction of the NV center-- aligned along one of four |
semiconductor subject to large bias voltages is therefore a |
possible directions in the diamond lattice. They reason that |
crucial step forward. |
a regular matrix of implanted NV centers should enable |
Nitrogen-vacancy centers |
reconstructing the electric field with a spatial resolution of about 10 nm by combining with super-resolution techniques, which is promising for studying more complex devices in further studies. |
Diamond consists of carbon atoms arranged on a lattice where each atom has four neighbors forming a tetrahedron. The diamond lattice is prone to defects; one such defect is the nitrogen-vacancy( NV) center, which can |
The researchers also point out that electric-field sensing is |
be thought of as resulting from replacing a carbon atom |
not only relevant for electronic devices, but also for |
with a nitrogen atom and removing one neighboring |
electrochemical applications: the efficiency of |
carbon atom. The energy level of an NV center lies in the |
electrochemical reactions taking place between a |
band gap of diamond but is sensitive to its local |
semiconductor and a solution depends on the former ' s |
environment. In particular, the so-called nuclear hyperfine |
internal electric field. In addition, Iwasaki and co-workers |
structure of an NV center depends on its surrounding |
note that their approach need not be restricted to NV |
electric field. This dependence is well understood |
centers in diamond: similar single-electron-spin structures |
theoretically, and was exploited by Iwasaki and co-workers: |
exist in other semiconductors like e. g. silicon carbide. |
detecting changes in an NV center ' s hyperfine structure |
|
Background
Wide-band-gap semiconductors
|
enabled them to obtain values for the local electric field. A major advantage of this approach is that it allows monitoring the field within the material-- not just at the |
Semiconducting materials feature a so-called band gap: an |
surface, for which methods had already been developed. |
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energy range wherein no accessible energy levels exist. In order for a semiconductor to conduct, electrons must acquire sufficient energy to overcome the band gap; controlling electronic transitions across the band gap forms the basis of semiconducting device action. Typical semiconductors like silicon or gallium arsenide have a band gap of the order of 1 electron volt( eV). Wide-band-gap semiconductors, like diamond or silicon carbide, have a larger band gap-- values as high as 3-5 eV are not uncommon.
Due to their large band gap, wide-band-gap
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Optically-detected magnetic resonance
For probing the nuclear hyperfine structure of an NV center in the bulk of the diamond-based device, Iwasaki and colleagues employed optically detected magnetic resonance( ODMR): by irradiating the sample with laser light, the NV center was optically excited, after which the magnetic resonance spectrum could be recorded. An electric field makes the ODMR resonance split; the experimentally detected split width provides a measure for the electric field.
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semiconductors can operate at temperatures over 300 ° C. | |
In addition, they can sustain high voltages and currents. | |
Because of these properties, wide-band-gap | |