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 . |
|
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 | |