Electronic structure of the shallow boron acceptor in 6H-SiC:mA pulsed EPR/ENDOR study at 95 GHz

Matsumoto, Toshiaki; Poluektov, Oleg G.; Schmidt, Jan; Мохов, Е. Н.; Баранов, П. Г.

doi:10.1103/physrevb.55.2219

Cited by 38 publications

(39 citation statements)

References 16 publications

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“…However, there is a striking difference between the EPR “spin signatures” of anion radicals (negative polarons) in PC 61 BM and PC 71 BM, namely, the unexpected shift of the g-values of the PC 71 BM anions compared to the PC 61 BM anions. In particular, as shown in Figure 1 and Table 1, all three PC 61 BM g-values are less than the free electron g-value, g e , similar to that of shallow-trapped electrons in semiconducting materials, 22, 23 while the PC 71 BM g-values are around or greater than g e , which is typical for shallow-trapped donors in semiconductors 24 or pure organic radicals. 25–27 …”

Section: Introductionmentioning

confidence: 72%

Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study

Mardis

Webb

Holloway

et al. 2015

J. Phys. Chem. Lett.

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Organic photovoltaic (OPV) devices are a promising alternative energy source. Attempts to improve their performance have focused on the optimization of the electron-donating polymers, while electron-accepting fullerenes have received less attention. Here, we report an electronic structure study of the widely used soluble fullerene derivatives PC61BM and PC71BM in their singly reduced state, that are generated in the polymer:fullerene blends upon light-induced charge separation. Density Functional Theory (DFT) calculations characterize the electronic structures of the fullerene anions through spin density distributions and magnetic resonance parameters. The good agreement of the calculated magnetic resonance parameters with those determined experimentally by advanced EPR spectroscopy allows the validation of the DFT calculations. Thus, for the first time the directions of the main g-tensors axis were determined in the molecular frame. For both systems, no spin density is present on the PCBM side chain and the axis of the largest g-value lies along the PCBM molecular axis. While the spin density distribution is largely uniform for PC61BM, it is not evenly distributed for PC71BM.

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Section: Introductionmentioning

confidence: 72%

Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study

Mardis

Webb

Holloway

et al. 2015

J. Phys. Chem. Lett.

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“…An alternative model like that in Matsumoto et al [17] for boron acceptors in 6H-SiC cannot be reconciled with the polarization characteristics in Fig. 3.…”

mentioning

confidence: 71%

Spontaneous Symmetry Breaking of Acceptors in “Blue” Diamonds

et al. 1999

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The electronic Raman transition between the lower 1s͑ p 3͞2 ͒ and the higher 1s͑ p 1͞2 ͒ state of a hole bound to a boron acceptor in diamond, examined under the high resolution of a Fabry-Pérot interferometer, reveals a doublet separated by ͑0.81 6 0.15͒ cm 21 , indicative of a spontaneous symmetry breaking of the fourfold degenerate ground state. The direct transition between the levels into which 1s͑ p 3͞2 ͒ : G 8 resolves, with a Raman shift of ͑0.80 6 0.04͒ cm 21 , provides a remarkable confirmation of the symmetry lowering shown to arise from a static Jahn-Teller distortion.

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“…The shallow acceptors introduced in SiC by the group-III impurities have been studied using electron paramagnetic resonance ͑EPR͒, [9][10][11][12][13][14][15][16] Optically Detected Magnetic Resonance ͑ODMR͒, [16][17][18][19][20] high-frequency pulsed EPR and electron-nuclear double resonance ͑ENDOR͒ at 95 GHz, 21 and by ENDOR at conventional frequencies. 22,23 It appears that the behavior of the sB acceptor is strikingly different from that of the shallow Al ͑sAl͒ and shallow Ga ͑sGa͒ acceptors.…”

Section: Introductionmentioning

confidence: 99%

“…15,16,21 It was proposed that B, which substitutes for Si but which has an atomic radius smaller than Si, occupies an off-center position owing to chemical rebonding, i.e., it relaxes away from the neighboring C along the B-C bond. Indeed a high-frequency ͑95 GHz͒ EPR and ENDOR study on sB in 6H-SiC revealed that there is a relaxation of the neighboring carbon atom and the boron atom away from each other.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of the deep boron acceptor in boron-doped6H-SiC

et al. 1998

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A high-frequency ͑95 GHz͒ and conventional-frequency ͑9.3 GHz͒ pulsed electron paramagnetic resonance and electron-nuclear double resonance ͑ENDOR͒ study is reported on the deep boron acceptor in 6H-SiC. The results support a model in which the deep boron acceptor consists of a boron on a silicon position with an adjacent carbon vacancy. The carbon vacancy combines with a boron along the hexagonal c axis. It is concluded that 70-90 % of the spin density resides in the silicon dangling bonds surrounding the vacancy and another 9% on the neighboring carbon atoms. The spin-density distribution is more localized than in the case of the shallow boron acceptor as deduced from the ENDOR experiments.

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Electronic structure of the shallow boron acceptor in 6H-SiC:mA pulsed EPR/ENDOR study at 95 GHz

Cited by 38 publications

References 16 publications

Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study

Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study

Spontaneous Symmetry Breaking of Acceptors in “Blue” Diamonds

Electronic structure of the deep boron acceptor in boron-doped6H-SiC

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