Couches minces de HgS obtenues par transport chimique en phase vapeur

Debiais, G.; Barceló, Juan A.; Aicardi, J.P.; Massé, G.; Bombré, F.

doi:10.1016/0040-6090(71)90010-1

Cited by 7 publications

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“…To investigate the influence of the growth direction on the protected surface-states, we calculated the electronic structure of the HgS-(110) surface, which is besides (001) another common surface of the zinc-blende structure 30 . We increased the slab thickness until the residual gap, which is due to the interaction of states at the two opposite surfaces, almost completely closed.…”

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Engineering Topological Surface States: HgS, HgSe, and HgTe

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Using density functional electronic structure calculations, we establish the consequences of surface termination and modification on protected surface-states of metacinnabar (β-HgS). Whereas we find that the Dirac cone is isotropic and well-separated from the valence band for the (110) surface, it is highly anisotropic at the pure (001) surface. We demonstrate that the anisotropy is modified by surface passivation because the topological surface-states include contributions from dangling bonds. Such dangling bonds exist on all pure surfaces within the whole class HgX with X = S, Se, or Te and directly affect the properties of the Dirac cone. Surface modifications also alter the spatial location (depth and decay length) of the topologically protected edge-states which renders them essential for the interpretation of photoemission data.PACS numbers: 72.80.Sk An attractive perspective for spintronics was opened up by the discovery 1-3 and manufacturing 4-6 of topological insulators (TIs). Inside, in its bulk, a TI is insulating but on its boundary -the material's edges, surfaces, or interfaces -a TI is conducting. The first TI in which the topological character of its edge-states was established is HgTe, a mercury chalcogenide material of the HgX family (where X=S, Se, Te) with a zinc-blende crystal structure 4 . The understanding of the precise properties of the topological edge-states in the HgX family of TIs -and an understanding of how these can be altered and engineered -is of fundamental importance in the field. It is of course also of direct relevance to the development of future spintronics applications, which aims to exploit the spin-momentum locking of TI boundary electrons 7,8 allowing for instance the generation of edge-spin-currents by circularly polarized light 9-11 . The precise location and electronic structure of the topological surface-states, in particular their dispersion, play furthermore an essential role in determining their spin-transport characteristics. It is for instance well-known that the momentum-spin locking usually renders disordered TIs poor spin conductors: When the electronic spin is tied to its momentum each scattering event randomizes the spin 12,13 . It was recently established that the resulting limit on spin relaxation time τ s for edge-state electrons strongly depends on their dispersion and momentum space anisotropy 14 .Here we show that for the HgX class of mercury-based II-VI semiconductors in the zinc-blende structure there is a strong influence of existing dangling bonds on the properties of topological surface-states. Thus, by surface passivation, it is possible to achieve a strong modification of the spatial location of the topological states, their rate of decay into the bulk, the resulting Dirac cone dispersion and, in particular, the Dirac cone anisotropy. Such alterations are possible because the presence of topological edge-states is absolutely fixed by the topological invariants of the bulk electronic structure, but the shape of their dispersion, their locat...

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Engineering Topological Surface States: HgS, HgSe, and HgTe

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“…Les vibrations de type A, et E sont seules actives en infrarouge, le type A, lorsque le rayonnement est polarise paralldement b l'axe c du cristal, le type E lorsque le rayonnement est polarise perpendiculairement & l'axe c. Les couches de sulfure de mercure dont nous disposons, prhsentent des plans d'accolement preferentiels mais ne sont pas Bpitaxiques, quel que soit le support, par suite de la coexistence des deux phases a et p [19]. I1 n'est donc pas possible de rbaliser une etude en lumihre polarisee pour distinguer le mode A,, du mode E du cinabre.…”

Section: Modes Normaux De Vibration Du Cinabreunclassified

“…Nous avons rBalis6 une Btude cristallographique [19] des couches mixtes de sulfure de mercure, mais elle n'est pas suffisamment prircise pour rbpondre b ces questions. En effet, l'Btude par diffraction des rayons X n'a rBvBlB que la proportion des cristallites appartenant b l'une ou l'autre phase et les plans d'accolement pr6ferentiels.…”

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Fonctions optiques d'une couche mince de sulfure de mercure

Debiais

1981

Physica Status Solidi (b)

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Fonctions optiques d'une couche mince de sulfure de mercure Par G. DEBIAIS Une mbthode de calcul des constantes optiques relative aux couches minces est analysbe et appliqube B une couche de sulfure de mercure renfermant 50% de cinabre (a-HgS) et 50% de mbtacinabre (p-HgS). Nous calculons les fonctions optiques et les frbquences des modes dans l'infrarouge entre 4000 et 250 cm-I et observons l'influence respective des deux formes sur ces rbsultats.A method for the calculation of the optical constants of thin films is analyzed and applied to a layer containing 50% of the cinnabar (a-HgS) and 50% of the metacinnabar (P-HgS). The optical functions are given in the infrared between 4000 and 250 cm-l, the mode frequencies are computed, and the influence of the two forms on these results is observed. Mkthode de calcul des constantes optiques Principe et justification de Z a me'thode choisieLes mkthodes de calcul des constantes optiques pour un milieu semi-infini sont classiques (mkthode des oscillateurs, inversion de Kramers-Kronig). Par contre, les mkthodes relatives aux couches minces sont beaucoup plus dklicates par suite des expressions compliquBes des facteurs de reflexion 31 et de transmission 3-. On les utilise souvent avec des approximations; Nakada [15], par exemple, les a tr&s convenablement appliqukes & des couches minces de sulfure de mercure dbposkes sur substrat transparent. La couche que nous Btudions d'bpaisseur 11,8 pm, est dbposbe sup verre, substrat opaque dans l'infrarouge. Nous sommes donc limitks L la seule mesure expkrimentale F-66025 Perpignan, France.

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Caractérisation optique et Blectrique de couches mixtes de sulfure de mercure Par

Debiais

1984

Phys. Stat. Sol. (a)

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Nous obtenons des spectres de reflexion dans I'infrarouge (4000 á 250 cm−1) et des caractéristiques électriques (coefficient de Hall, résistivité, mobilityé) á partir de couches mixtes de sulfure de mercure. L'interprétation de ces données conduit á la détermination de la fréquence plasma, de la denaité des porteurs et de la masse effective. L'évolution de ces résultate avec la variation du pourcentage des phases α et β est analysée et compareée aux résultats connus sur les cristaux purs.

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Couches minces de HgS obtenues par transport chimique en phase vapeur

Cited by 7 publications

References 3 publications

Engineering Topological Surface States: HgS, HgSe, and HgTe

Engineering Topological Surface States: HgS, HgSe, and HgTe

Fonctions optiques d'une couche mince de sulfure de mercure

Caractérisation optique et Blectrique de couches mixtes de sulfure de mercure Par

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