Transport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitation

Rajevac, V.; Boehme, Christoph; Michel, C.; Gliesche, A.; Lips, K.; Baranovskiǐ, S. D.; Thomas, P.

doi:10.1103/physrevb.74.245206

Cited by 29 publications

(70 citation statements)

References 22 publications

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“…For instance, the study of beat oscillations of charge-carrier spin-Rabi nutation in the conductivity of diode structures based on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) has been repeated in optical recombination by pODMR spectroscopy through transient detection of photoluminescence intensity changes [41]. This comparison revealed qualitatively identical observations to pEDMR [14] of a pronounced spin-dependent transition rate which displays the same double Gaussian resonance lines, the same Rabi nutation of spin manifolds with s=1/2 as well as distinct beat oscillations, indicative that the observed spin systems belong to weakly coupled pairs with negligible dipolar and exchange coupling [42] [15]. While this experiment unambiguously proves that weakly coupled electron-hole pairs are involved in recombination, and thus luminescence, under the low-temperature conditions where measurements were made, the results do not unambiguously prove that the weakly coupled room-temperature charge carrier spin pairs observed with pulsed EDMR are also of opposite charge and not bipolarons.…”

Section: Introductionsupporting

confidence: 59%

Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

et al. 2016

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Spin-dependent processes play a crucial role in organic electronic devices. Spin coherence can give rise to spin mixing due to a number of processes such as hyperfine coupling, and leads to a range of magnetic field effects. However, it is not straightforward to differentiate between pure single-carrier spin-dependent transport processes which control the current and therefore the electroluminescence, and spin-dependent electron-hole recombination which determines the electroluminescence yield and in turn modulates the current. We therefore investigate the correlation between the dynamics of spin-dependent electric current and spin-dependent electroluminescence in two derivatives of the conjugated polymer poly(phenylene-vinylene) using simultaneously measured pulsed electrically detected (pEDMR) and optically detected (pODMR) magnetic resonance spectroscopy. This experimental approach requires careful analysis of the transient response functions under optical and electrical detection. At room temperature and under bipolar charge-carrier injection conditions, a correlation of the pEDMR and the pODMR signals is observed, consistent with the hypothesis that the recombination currents involve spin-dependent electronic transitions. This observation is inconsistent with the hypothesis that these signals are caused by spin-dependent charge carrier transport. These results therefore provide no evidence that supports earlier claims that spindependent transport plays a role for room temperature magnetoresistance effects. At low temperatures, however, the correlation between pEDMR and pODMR is weakened, demonstrating that more than one spin-dependent process influences the optoelectronic materials properties. This conclusion is consistent with prior studies of half-field resonances that were attributed to spin-dependent triplet exciton recombination which becomes significant at low temperatures when the triplet lifetime increases. PACS

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Section: Introductionsupporting

confidence: 59%

Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

et al. 2016

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“…3(c), we obtain a proportionality factor of γ exp = (1.03 ± 0.08)γ. Since the ratio Ω/γB 1 is greater than 1 for strongly coupled systems [26], the experimentally observed Ω/γB 1 ≈ 1 indicates a weakly coupled spin pair.…”

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confidence: 99%

Electrical detection of coherent 31P spin quantum states

et al. 2006

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In recent years, a variety of solid-state qubits has been realized, including quantum dots [1,2], superconducting tunnel junctions [3,4] and point defects [5,6]. Due to its potential compatibility with existing microelectronics, the proposal by Kane [7,8] based on phosphorus donors in Si has also been pursued intensively [9,10,11]. A key issue of this concept is the readout of the 31 P quantum state. While electrical measurements of magnetic resonance have been performed on single spins [12,13], the statistical nature of these experiments based on random telegraph noise measurements has impeded the readout of single spin states. In this letter, we demonstrate the measurement of the spin state of 31 P donor electrons in silicon and the observation of Rabi flops by purely electric means, accomplished by coherent manipulation of spin-dependent charge carrier recombination between the 31 P donor and paramagnetic localized states at the Si/SiO2 interface via pulsed electrically detected magnetic resonance. The electron spin information is shown to be coupled through the hyperfine interaction with the 31 P nucleus, which demonstrates the feasibility of a recombinationbased readout of nuclear spins.Since the detection of single charges has become technically straight forward, it is widely believed [7,8,10,11,12] that the realization of spin-to-charge transfer is the key prerequisite for a successful implementation of single spin phosphorus ( 31 P) readout devices, capable of determining the actual spin state (spin up | ↑ or spin down | ↓ ). Different approaches to the electrical spin readout of 31 P-donor electron spins have been proposed based on spin-dependent transitions between neighboring 31 P atoms [7,8,10,11]. Since the states involved are energetically degenerate, these spin-to-charge transfer schemes are rather difficult to realize. Alternatively, spin-dependent transitions involving dissimilar paramagnetic states might be easier to detect as proposed by Boehme and Lips [14]. Spin-dependent charge carrier transport and recombination are known at least since 1966 [15], when Schmidt and Solomon already observed spin-dependent recombination involving 31 P donors in silicon. However, it was not demonstrated until 2003 [16] that the much more sensitive electrical detection of spins via resonant changes of recombination processes is also able to reflect coherent spin motion, which is necessary for a readout of the spin quantum state as opposed to a mere detection of the presence of spins. Figure 1(a) illustrates the readout scheme based on spin-dependent recombination demonstrated in this paper. In order to probe 31 P donor electron spins, spindependent excess charge carrier recombination through so-called P b0 centers is used. P b0 centers are trivalent Si atoms at the interface between crystalline silicon (c-Si) and silicon dioxide (SiO 2 ) that introduce localized, paramagnetic states in the Si band gap and dominate electron trapping and recombination at the interface [17,18]. If a neutral P b0 center is locate...

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“…We note that the transition from a 31 P−P b process 7 at low fields to a P b only mechanism at high fields may be explained by considering the underlying spin dynamics. The strength of an EDMR signal becomes weaker as the ratio ξ = ∆ω γB 1 of the difference of the Larmor frequencies in a pair, ∆ω, to γB 1 drops below 1, with γ being the gyromagnetic ratio 19 . Hence, at low fields EDMR signals are dominated by maximized 31 P−P b signals as ξ > 1 while ξ ≪ 1 for the P b pairs with ∆ω ≪ γB 1 due to the almost identical Landé-factors of two P b centers.…”

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confidence: 99%

Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

et al. 2008

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An experimental study on the nature of spin-dependent excess charge carrier transitions at the interface between (111) oriented phosphorous doped ([P]≈ 10 15 cm −3 ) crystalline silicon and silicon dioxide at high magnetic field (B 0 ≈ 8.5T) is presented. Electrically detected magnetic resonance (EDMR) spectra of the hyperfine split 31 P donor electron transitions and paramagnetic interface defects were conducted at temperatures in the range 3 K≤ T ≤12 K. The results at these previously unattained (for EDMR) magnetic field strengths reveal the dominance of spin-dependent processes that differ from the previously well investigated recombination between the 31 P donor and the P b state, which dominates at low magnetic fields. While magnetic resonant current responses due to 31 P and P b states are still present, they do not correlate and only the P b contribution can be associated with an interface process due to spin-dependent tunneling between energetically and physically adjacent P b states. This work provides an experimental demonstration of spin-dependent tunneling between physically adjacent and identical electronic states as proposed by Kane for readout of donor qubits. 71.55.Cn, 73.40.Qv Phosphorus doped crystalline silicon (c-Si:P) is one of the most widely utilized semiconductor materials, with applications ranging from conventional microelectronics 1 to proposed and presently widely investigated concepts for spintronics 2 and spin-based quantum information processing (QIP) 3 . Silicon based spin-QIP and spintronics concepts aim to utilize the comparatively weak spin-orbit coupling present in this material, and the correspondingly very long spincoherence times 2,3 , as well as the impact of spin-selection rules on electronic transitions which can be used for spin readout 4 . Most of these applications involve electrical transport and spin manipulation at or near the silicon-silicon dioxide (SiO 2 ) interface, making the understanding of spin processes in this region extremely important. Numerous studies of spin-dependent transport and recombination at the interface between c-Si:P and SiO 2 have recently been undertaken, with the aim of identifying and understanding these mechanisms 5,6,7 , and showing that they can be utilized for the observation of very small ensembles of donors 8 and coherent spin motion 7,9 . Additionally, spin dependent transport in two dimensional electron gases at the c-Si/SiO 2 interface has been demonstrated 10,11 . However, no systematic study of such processes at high magnetic field has been conducted to date, with the only data at magnetic fields B 0 > 400 mT given by a single electrically detected magnetic resonance (EDMR) spectrum recorded at B 0 = 7.1 T and a temperature T = 4 K 12 .In the following, a systematic investigation of the spin dependent processes at the interface between c-Si:P and SiO 2 are presented for high magnetic fields (B 0 ≈ 8.5 T) at temperatures in the range 3 K≤ T ≤12 K.We show that the dominant spin-dependent recombination mechanism at low magnet...

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Transport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitation

Cited by 29 publications

References 22 publications

Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

Electrical detection of coherent 31P spin quantum states

Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

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