We present a systematic theoretical study of spindependent recombination and its effect on optical orientation of photoelectron spins in semiconductors with deep paramagnetic centers. Spindependent and localisation effects at sisio 2 device interfaces b henderson, m pepper and r l vranchrecent citations investigation of electronic transitions in semiconductors with pulsed electrically detected magnetic resonance c. Chapter four describes characterization techniques utilized in this work. A theory of spinpolarized transport in inhomogeneous magnetic semiconductors is developed and applied to magneticnonmagnetic pn junctions. H and chalcogenides, quantum phenomena in multilayer films.
Apr 16, 2014 this demonstration is explained quantitatively within a theory of spin dependent exciton recombination in the organic semiconductor, driven primarily by gradients in the remanent fringe fields of. Discrimination between spindependent charge transport and. Dynamics of spindependent charge carrier recombination. Spindependent phenomena in semiconductors, 2d materials. By simultaneously exposing the device to a large magnetic field h and microwave irradiation of. Broadly speaking, spindependent transport phenomena in semiconductors can be divided into two categories. Spin filter in spindependent recombination and nuclear effects. Asenov department of electrical and electronic engineering, university of giasgow g12 8qq scotland. Sdr exploits the fact that recombination in semiconductors is spin dependent lepine, 1972. Analytical expressions have been derived that describe the coulomb. Review article singlet generation from triplet excitons in fluorescent organic lightemitting diodes a. Spindependent recombination and hyperfine interaction at the. For this aim we generalize the shockleyread theory of recombination of electrons and holes.
Roomtemperature spindependent recombination in a series of gaas1. To construct a detailed picture of this process, we consider a system of ct states which are generated optically, that is, in either of the spin antiparallel configurations, and undergo spin dependent recombination under the influence of microwave driving. H, mechanisms for lightinduced defect creation in asi. It is found that the photoluminescence circular polarization determined by the mean spin of free electrons reaches 4045% and this giant value persists within 2 ns. Vxqghufrqwlqxrxv zdyhsxpslqj optical spin pumping of qws. The effect of spin dependent recombination on the transport properties of magnetic semiconductors is investigated theoretically. Twodimensional groupvi transition metal dichalcogenide semiconductors, such as mos2, wse2, and others, exhibit strong lightmatter coupling and possess direct band gaps in. Spin filter in spindependent recombination and nuclear.
For this aim we generalize the shockleyread theory of recombination of electrons and holes through the deep centers with allowance for opticallyinduced spin. Spin dependent recombination at deeplevel centers in 6h silicon carbidesilicon metal oxide semiconductor field effect transistors p. Spindependent recombination among chargetransfer states. Figure 1 illustrates the mechanism for enhancing the carrier lifetime in a generic 3d rashba material. The relative spin orientation of these 505 506 theory of spin dependent recombination in semiconductors vol. In particular, for ptype direct band gap semiconductors, a theory based on classic shockley equations is formulated. A theory of spin polarized transport in inhomogeneous magnetic semiconductors is developed and applied to magneticnonmagnetic pn junctions. Electrically detected magnetic resonance wikipedia. Complete theoretical analysis of the kaplansolomonmott. Daniel kaplan born april 28, 1941 is a french condensed matter physicist whose main work concerns the electronic properties of semiconductors, magnetic resonance and ultrashort pulse lasers. All of the quantities in these expressions can be calculated using existing electronic structure. The study presented deals with the dynamics of spindependent charge carrier recombination between localised bandgap states in semiconductors. Hence, with the help of the external magnetic field we can control the orientation of unpaired electron and consequently the spin dependent recombination in the defects.
The theory takes into account all reencounters of two radicals. Furthermore, spindependent transport processes will affect optical emission only indirectly by changing the device current and thus, as discussed quantitatively below, are separable from spindependent recombination. We report on both experimental and theoretical study of conductionelectron spin polarization dynamics achieved by pulsed optical pumping at room temperature in gaas1. Lipstheory of timedomain measurement of spindependent recombination with pulsed. Spindependent phenomena in semiconductors, 2d materials and.
In this theory the density of spin and charge has been evaluated analytically by solving the diffusive transport equation and it is shown that the. Davies, 1979, the behaviour of donoracceptor recombination emission in iivi crystals subjected to magnetic resonance, journal of physics c. Our approach to spin dependent carrier recombination has many similarities to the theory of these effects 17, 18 and to that of the closely related. Also, we present an experimental result that may imply the spindependent opencircuit voltage in organic bilayer photovoltaic devices. For more information on dark deposits, see our faq. The relative spin orientation of these 505 506 theory of spindependent recombination in semiconductors vol. Following the successful edition of last year, the symposium will give again the opportunity to discuss about the latest research efforts and developments related to spindependent phenomena in semiconductors including 2d materials and their heterostructures as well as topological insulators. In this case, device current changes will, of course, also induce recombination rate changes. Spin and magnetic field effects in organic semiconductor.
We present a theoretical study of optical electron spin orientation and spin dependent shockleyreadhall recombination taking into account the hyperfine coupling between the boundelectron spin and the nuclear spin of a deep paramagnetic center. We propose using spin dependent shockleyread recombination via deep paramagnetic centers in order to achieve very high up to 100% both electron and nuclear spin polarization in nonmagnetic semiconductors at room temperature and zero and weak magnetic fields motivation 2. Pdf crystalline silicon with a large dislocation density shows a very complex magneticresonance spectrum. Theory of spindependent recombination in semiconductors. Introduction as has already been noted, kaplan, solomon, and mott12 have proposed for spin dependent recombination in semiconductors a new model based on the assumption that the recombination proceeds via the bound state of the elec. Spindependent recombination and hyperfine interaction at. Besides the topological robustness against fabrication imperfections, a programmable device is designed to. Negativeucenters in 4h and 6hsic detected by spectral light excitation. For the spindependent reactions in organic semiconductors we would like to model, usually two types of interactions are present in the hamiltonian.
The authors describe three spin and magnetic field effects in organic semiconductor devices. Theoretical evaluation of spindependent auger deexcitation. Optical orientation and spindependent recombination in. Meyer physikdepartment, technical university munich, e 16, d8046 garching, federal republic of germany a. Spin dependent recombination at deeplevel centers in 6h. Microscopic modeling of magneticfield effects on charge transport in organic semiconductors citation for published version apa. Basic principles of the spin dependent recombination sdr are introduced in chapter three. The kinetic equations of spindependent radical recombination are described. Spin dependent recombination in ptdoped silicon pn junctions. Conventional epr measurements generally require strong static magnetic fields, typically 3 kg or greater, and high frequency oscillating electromagnetic. On the one hand, we have those effects such as spin drift, spin diffusion, and spin precession that refer to the transport of spinpolarized carriers. Electrically detected magnetic resonance edmr is a materials characterisation technique that improves upon electron spin resonance. A large portion is devoted to the latest developments of amorphous semiconductors including electronic properties of asi.
Basic principles of the spindependent recombination sdr are introduced in chapter three. It involves measuring the change in electrical resistance of a sample when exposed to certain microwave frequencies. Spin dependent recombination in magnetic semiconductor. First, injection, transport and detection of spinpolarised carriers using an organic semiconductor as the spacer layer in a spinvalve structure, yielding lowtemperature giant magnetoresistance effects as large as 40%. In particular, for ptype direct band gap semiconductors, a theory. Jun 17, 2009 the effect of spin dependent recombination on the transport properties of magnetic semiconductors is investigated theoretically. Introduction as has already been noted, kaplan, solomon, and mott12 have proposed for spindependent recombination in semiconductors a new model based on the assumption that the recombination proceeds via the bound state of the elec. Spindependent recombination probed through the dielectric. Spindependent donoracceptor pair recombination in zns crystals showing the selfactivated emission, journal of physics c. Complete theoretical analysis of the kaplansolomonmott mechanism of spin dependent recombination in semiconductors. Theory of spindependent recombination of radicals in. In article number 1904682, ying cheng, xiaojun liu, johan christensen, and co.
Spin dependent recombination was recently studied as a single quantum transition with no energy relaxation. Analysis of ionized cluster beam thin film deposition, dave turner. This demonstration is explained quantitatively within a theory of spindependent exciton recombination in the organic semiconductor, driven primarily by gradients in the remanent fringe fields of. Spindependent electron dynamics and recombination in gaas1. The kinetic equations of spin dependent radical recombination are described. We show that the number of master rate equations for the components of the electronnuclear spindensity matrix is considerably reduced due to the. Spindependent transport of carriers in semiconductors. Spindependent recombination and electroluminescence quantum. Zerofield detection of spin dependent recombination with.
Charge recombination in organic smallmolecule solar cells. Spin dependent and localisation effects at sisio 2 device interfaces b henderson, m pepper and r l vranchrecent citations investigation of electronic transitions in semiconductors with pulsed electrically detected magnetic resonance c. Broadly speaking, spin dependent transport phenomena in semiconductors can be divided into two categories. Quantitative model of spin dependent recombination. We propose using spindependent shockleyread recombination via deep paramagnetic centers in order to achieve very high up to 100% both electron and nuclear spin polarization in nonmagnetic semiconductors at room temperature and zero and weak magnetic fields motivation 2. Exciton physics and device application of twodimensional. A variable dc bfield is applied along with an ac microwave signal at 9. Ga 2o 3 films, 235 international union of crystallography, 12 k. Several phenomena with possible spintronic applications are predicted, including spinvoltaic effect, spin valve effect, exponential and giant magnetoresistance. It can be used to identify very small numbers down to a few hundred atoms of impurities in semiconductors. Spindependent recombination was recently studied as a single quantum transition with no energy relaxation. Review article singlet generation from triplet excitons in.
The experimental setup for sdr is similar to esr experimental setup. This spindependent recombination mechanism highlights the possibility of using 3d rashba materials38. Electrically detected magnetic resonance edmr involves the electron paramagnetic resonance epr study of spin dependent transport mechanisms such as spin dependent tunneling and spin dependent recombination sdr in solid state electronics. Spin dependent recombination in conjugated polymers. Nonequilibrium electron polarization and maser effect in spindependent recombination through exchangecoupled pairs v. At the lowest microwave powers we observe the response expected for a system which contains exclusively free chargesan antisymmetric lorentzian lineshape proportional to the real. Furthermore, spin dependent transport processes will affect optical emission only indirectly by changing the device current and thus, as discussed quantitatively below, are separable from spin dependent recombination. The magnetic field dependence of the recombination rate constants is calculated in two cases. Our approach to spindependent carrier recombination has many similarities to the theory of these effects 17, 18 and to that of the closely related. Organic magnetoelectroluminescence for room temperature. Spindependent recombination in gaasn solid solutions. The measurements are made by configuring a device in such a way that the device current is dominated by recombination events. Evidence for a deep two charge state defect in high energy electron irradiated 4hsic p.
Spin dependent recombination in ganas yuttapoom puttisong. Spindependent electron dynamics and recombination in gaas. Sep 10, 2018 twodimensional groupvi transition metal dichalcogenide semiconductors, such as mos2, wse2, and others, exhibit strong lightmatter coupling and possess direct band gaps in the infrared and. We show that the number of master rate equations for the components of the electronnuclear spin density matrix is considerably reduced due to the. We present a theoretical study of optical electronspin orientation and spindependent shockleyreadhall recombination taking into account the hyperfine coupling between the boundelectron spin and the nuclear spin of a deep paramagnetic center. Nonequilibrium electron polarization and maser effect in. Microscopic modeling of magneticfield effects on charge. Spindependent recombination and electroluminescence. Uk semiconductors 2015 technical programme we are pleased to welcome our four highprofile international plenary speakers who will provide extended presentations of general interest to delegates on topics including quantum dot lasers, 2d materials, nitride.
The spin dependent recombination through the paramagnetic state of a localised recombination centre, detected by a resonant change in the photocurrent in silicon was reported. Rashba spin orbit coupling enhanced carrier lifetime in nh pbi. This demonstration is explained quantitatively within a theory of spindependent exciton recombination in the organic semiconductor, driven primarily by gradients in the remanent fringe. We have previously4 used this model to calcu late the rate of the spin dependent recombination as a func tion of the strength of the magnetic field for the case in which the spin hamiltonian of the pair has only the zeeman energy. We show with a simulation that the spindisallowed recombination process increases the charge collection efficiency. Nonequilibrium electron polarization and maser effect in spin. The pair model of spindependent recombination of carriers in semiconductors, as discussed by kaplan, solomon and mott, is solved exactly in several l. Physics of amorphous semiconductors world scientific. On the one hand, we have those effects such as spin drift, spin diffusion, and spin precession that refer to the transport of spin polarized carriers. Several phenomena with possible spintronic applications are predicted, including spin voltaic effect, spin valve effect, exponential and giant magnetoresistance.
Complete theoretical analysis of the kaplansolomonmott mechanism of spindependent recombination in semiconductors. Physics and astronomy theses and dissertations physics. Monkman organic electroactive materials research group, department of physics, university of durham, durham dh l e, uk correspondence should be addressed to a. Lips theory of timedomain measurement of spin dependent recombination with pulsed.
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