Figure 1.
(a) Conceptualized illustration of SDR in a pn junction where singlet-triplet pairs form in the presence of a nuclear magnetic field BN and a small external magnetic field B. The local field BL experienced by each electron is the vector sum of both of these field components. Conduction electrons will couple with unpaired defect electrons for a finite amount of time forming either triplet or singlet states. Because the capture event, leading to eventual recombination, involves zero change in angular momentum, only singlet pairs will lead to recombination whereas triplet pairs dissociate. Because triplet pairs exist for a finite amount of time, radiative (magnetic resonance) or non-radiative transitions from triplet pairs to singlet pairs may occur which can increase the capture rate and thus the recombination rate. The latter occurs due to the mixing of states that results when the spin sites have slightly different local fields. See Table 1. (b) Comparison of the SDR response acquired via high-field EDMR (B0 = 340.3 mT, v = 9.54 GHz, Bm = 0.2 mT) and it’s corresponding model (see text for description). Note that the equally spaced satellite peaks, indicated by the vertical arrows spaced 1.1 mT apart, are consistent with a doublet involving hydrogen. (c, top) Comparison of the high-field EDMR and ZFSDR responses when biased with 2.4 V. (c, bottom). Energy levels of the spin Hamiltonian matrix, given by Table 1, evaluated over a small range of magnetic fields using hyperfine parameters obtained from the high-field EDMR model. Note that the hyperfine peaks illustrated in the ZFSDR response are precisely located at magnetic fields which correspond to crossing of singlet and triplet energy levels.