Process of SDR in a pn junction via paramagnetic deep level defects through the formation of spin pairs. (a): (1) conduction electron and defect electron couple to form a triplet pair, (2) pair dissociates because recombination is forbidden. (b): (1) conduction electron and defect electron couple to form a singlet pair, (2) because angular momentum is conserved, recombination of electron and hole is now possible. (c) Top view photograph and (d) simplified illustration of the cross sectional view of the device used in this study.
Low-field detection of SDR via EDMR compared to zero-field detection of SDR. (a) 3D mesh of representative EDMR scans on a SiC diode for a series of B1 amplitudes. (b) Amplitude of the zero-field and low-field resonant signals as a function of B1 . The EDMR amplitudes increase monotonically with increasing B1 . Note that the increase in the B1 field saturates the resonant SDR response but doesn't affect the amplitude of the zero-field response. (c) Comparison of low-field scans acquired with (top, blue) and without (red, bottom) RF radiation applied. The arrows in the resonant trace indicate the Breit-Rabi shift of the normally (high-field) isotropic hyperfine peaks at low-fields. (d) Comparison of the derivative of a spectrum acquired without any modulation (blue, top) and the spectrum obtained from a 1 kHz, 2 Gauss modulation (red, bottom).
(a) First derivative of spectra observed at zero field (blue) and at X band (red) taken at 9.5 GHz, 3394 Gauss. (b) Second derivative of the spectra illustrated in (a). Note that each peak observed at X band is also seen in the zero field spectrum. (c) Zero-field and (d) derivative of spectrum acquired with low modulation amplitude (∼ 0.25 Gauss). Note the deviation in slope at precisely zero Gauss illustrated by inset of (c) which shows up as a double peak in (d).
This set of figures illustrates the behavior of the zero-field response as a function of applied bias. (a) Simulation of the recombination current for a 4H SiC diode at room temperature. (b) Illustration of the peak-to-peak amplitude of the zero-field signal as a function of applied bias plotted against the simulated recombination current displayed in (a) and the DC diode current. The close similarity of the plots demonstrates that this phenomenon is a recombination process. (c) The percent change in the zero-field SDR current acquired by dividing the peak-to-peak amplitude by the dc current as a function of bias voltage. Note that this response peaks at 2.35 volts with a relatively large change of almost 1%. (d) Integrated spectra acquired for the data plotted in (b) and (c). Note that as the bias is increased beyond the built-in voltage (Va ≥ 2.65 V), the SDR signal begins to decrease. Note also that beyond this voltage, a double peak appears to be forming. The four traces on the inset of this figure illustrate the transition of the single peak into two.
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