Complex isotope splitting of the no-phonon lines associated with exciton decay at a four-lithium-atom isoelectronic centre in silicon

Canham, Leigh; Davies, Gordon; Lightowlers, E C; Blackmore, G. W.

doi:10.1016/0378-4363(83)90458-8

Cited by 13 publications

(5 citation statements)

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“…This kind of complicated splitting is not observed for the first time. In Li-doped silicon, where similar splitting due to isotope substitution was found [41,24]. For the Li 4 complex, two types of splitting was found.…”

Section: Isotope Splittingsupporting

confidence: 61%

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A new structure of Cu complex in Si and its photoluminescence

Shirai

Yamaguchi

Yanase

et al. 2009

J. Phys.: Condens. Matter

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A recent discovery of complicated isotope shifts of the PL 1014 meV line in Cu-containing silicon, which was made by Thewalt's group, indicates that existing models of Cu pairs are not appropriate for accounting for the luminescence center. A new structural model has been studied. First-principles calculations show that the most probable form of the complex is a four-membered complex which is composed of a substitutional Cu associated with three neighboring interstitial Cu atoms. The symmetry is C(3v). The formation mechanism of this complex is discussed. For interpreting the complicated splitting for the Γ(4) exciton peak, involvement of a non-totally symmetric mode is proposed. The pattern of splitting obtained by this model is almost in agreement with the experiment. Selection rules beyond the usual treatments are necessary to connect a specific exciton peak to the corresponding phonon.

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Section: Isotope Splittingsupporting

confidence: 61%

“…A four-membered complex is not at all unusual. It was reported that Li and Br form such complexes [41]. In these cases, however, for example, four Li atoms get together around a vacancy, i.e.…”

Section: Discussionmentioning

confidence: 99%

A new structure of Cu complex in Si and its photoluminescence

Shirai

Yamaguchi

Yanase

et al. 2009

J. Phys.: Condens. Matter

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“…Most probable is the trigonal distorsion leading to a stable geometrical configuration of C,, or D,, symmetry. The C,, symmetry is in agreement with experimental observations [12].…”

Section: Results Of Calculationssupporting

confidence: 90%

“…There are several theoretical papers dealing with the behavior of lithium in silicon. Canham et al [12] have studied luminescence spectra of vacancy + Li complexes in silicon. The dependence of the line splitting on uniaxial pressure in different orientations permitted by the C,, symmetry assignment to this complex.…”

Section: Introductionmentioning

confidence: 99%

Study of Lithium Interaction with Lattice Defects in Silicon

Myakenkaya

Gutsev

Afanas'eva

et al. 1990

Physica Status Solidi (b)

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A theoretical and experimental study is carried out on the behaviour of the Li donor impurity in the Si lattice with vacancy-like (V) radiation-induced defects. The electronic and geometrical structure of the cluster Si,H,, + Li, simulating the V f Li, complex in Si is calculated by the discrete variational X,-method. It is found that the cubic tetrahedral configuration of the complex is geometrically stable where the 8t2 state near the edge of the valence band is completely populated. The principal possibility of passivation of the V-type defects by Li atoms is checked experimentally on n-and p-Si samples with a Li concentration of x 1017 cm-' irradiated by reactor neutrons at fluences of 1.6 x and 3.4 x 10l6 cm-3. The temperature dependences of the conductivity, Hall constant, and mobility are measured. It is shown that at high Li atom concentrations considerably in excess of the concentration of the dopant and radiation-induced defects the electrical characteristics of the irradiated Si restore to the original level which is in agreement with the calculations on the passivation of the Li atoms by the V-states in Si.Das Verhalten der Li-Donatorstorstelle im Si-Gitter mit leerstellenahnlichen (V), strahlungsinduzierten Defekten wird theoretisch und experimentell untersucht. Die elektronische und geometrische Struktur des Clusters Si,HI2 + Li,, der den V + Li,-Komplex in Si simuliert, wird mit der diskreten X,-Variationsmethode berechnet. Es wird gefunden, daS die kubisch tetraedrische Konfiguration des Komplexes geometrisch stabil ist, wobei der 8t,-Zustand in der Nahe der Valenzbandkante vollstandig besetzt ist. Die prinzipielle Moglichkeit der Passivierung der V-Defekte durch Li-Atome wird experimentell uberpriift an n-und p-leitenden Si-Proben mit Li-Konzentrationen von 1017 aW3, die mit Reaktorneutronen bei Flussen von 1,6 x 10'' , 4 x loL5 und 3,4 x 1OI6 cm-3 bestrahlt wurden.Die Temperaturabhangigkeiten der Leitfahigkeit, Hall-Konstante und Beweglichkeiten werden gemessen. Es wird gezeigt, daI3 bei hohen Li-Atomkonzentrationen, die die Konzentration der Dotanden und strahlungsinduzierten Defekte betrachtlich ubersteigen, sich die elektrischen Charakteristiken des bestrahlten Si auf das urspriingliche Niveau zuruckbilden, was in obereinstimmung mit den Berechnungen zur Passivierung der Li-Atome durch die V-Zustande in Si ist.

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“…The complex is stable once it has formed due to its very low formation energy, and some experimental evidence exists for such a defect. 22 We attribute the stability of {4Li,V } to it satisfying the Zintl rules for intermetallic chemical bonding, and other defects such as {Li,V }, {2Li,V }, and {3Li,V } are substantially higher in energy. In scenarios (i) and (ii), the vacancy is formed alongside the inclusion of lithium.…”

Section: })mentioning

confidence: 97%

Lithiation of silicon via lithium Zintl-defect complexes from first principles

et al. 2013

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An extensive search for low-energy lithium defects in crystalline silicon using density-functional-theory methods and the ab initio random structure searching (AIRSS) method shows that the four-lithium-atom substitutional point defect is exceptionally stable. This defect consists of four lithium atoms with strong ionic bonds to the four under-coordinated atoms of a silicon vacancy defect, similar to the bonding of metal ions in Zintl phases. This complex is stable over a range of silicon environments, indicating that it may aid amorphization of crystalline silicon and form upon delithiation of the silicon anode of a Li-ion rechargeable battery. }).For example, the lithium substitutional defect is denoted by {Li,V } since it comprises a lithium atom within a silicon vacancy. A lithium-vacancy complex was assigned to an electron paramagnetic resonance (EPR) center by Goldstein 2 and lithium drift rate experiments have also shown that lithium binds to vacancies, preventing further mobility.3 Our density-functional-theory (DFT) calculations show that the formation of a Frenkel-type impurity defect ({Li,V ,I }) from a T d interstitial Li atom requires an energy of 3.73 eV, which is in excellent agreement with the value of 3.75 eV calculated by Wan et al. 4 Wan et al. suggested that the substitutional lithium defect, {Li,V } will not form due to its large formation energy. However, we calculate its formation energy from bulk silicon and lithium metal to be 3.09 eV, and hence {Li,V } is more stable than a separated vacancy and lithium interstitial ({V } and {Li}). It is likely that silicon vacancies play a significant role in the interaction between lithium and silicon.Along with the wide range of technological uses of silicon, such as semiconductor devices and photovoltaics, it has recently been proposed as an anode for lithium-ion batteries. Lithium intercalated graphite is the standard lithium-ion battery (LIB) negative electrode material, due to its good rate capability and cyclability, but demand for even higher performance LIBs has motivated the investigation of other materials. Silicon is an attractive alternative since it has 10 times the gravimetric and volumetric capacity of graphite (calculated from the initial mass and volume of silicon) but, unlike graphite, silicon undergoes structural changes on lithiation. 5-7In the first stages of lithiation, in which silicon atoms greatly outnumber lithium, it has been proposed that lithiation occurs as interstitial lithium defects form near the silicon surface. 8 Previous theoretical studies have shown that a single lithium atom in bulk silicon resides at the T d site and that at higher concentrations lithium clusters can promote the breaking of silicon-silicon bonds. 4,9,10 There are equal numbers of T d sites and silicon atoms in c-Si and, since a-Li y Si forms at y ≈ 0.3 in micron-sized silicon clusters (a Li:Si ratio of ≈ 1 : 3 11,12 ), the presence of lithium must lead to the breaking of silicon-silicon bonds before all T d sites are filled with lithium. Chan e...

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Complex isotope splitting of the no-phonon lines associated with exciton decay at a four-lithium-atom isoelectronic centre in silicon

Cited by 13 publications

References 2 publications

A new structure of Cu complex in Si and its photoluminescence

A new structure of Cu complex in Si and its photoluminescence

Study of Lithium Interaction with Lattice Defects in Silicon

Lithiation of silicon via lithium Zintl-defect complexes from first principles

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