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Semiconductores solubles AAsSe2 (A = Li, Na) con una brecha de banda directa y una fuerte generación de segundos
Tarun K Bera1, Joon I Jang, Jung-Hwan Song
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|February 23, 2010
Resumen
Los nuevos alcalino-metálicos chalcoarsenados (AAsSe2) son semiconductores polares con espacios de banda sintonizables. Gamma-NaAsSe2 exhibe excepcionales propiedades ópticas no lineales, lo que hace que estos materiales sean prometedores para el procesamiento de soluciones.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química del estado sólido.
- Física de los semiconductores Física de los semiconductores
Sus antecedentes:
- Descubrimiento de una nueva clase de calcoarsenatos ternales de metales alcalinos, AAsSe2 (A = Li, Na).
- Estos compuestos cuentan con infinitas cadenas individuales de unidades [AsQ2](-) con pares aislados estereoquímicamente activos en el arsénico.
- La diversidad estructural surge de la influencia de los metales alcalinos, lo que lleva a al menos cuatro tipos estructurales distintos en Li{1-x) Na{x) AsSe2.2.
Objetivo del estudio:
- Caracterizar las propiedades estructurales, electrónicas y ópticas de los materiales AAsSe2.
- Investigar la relación entre la composición, la estructura y las propiedades de los semiconductores.
- Explorar el potencial de estos materiales para aplicaciones ópticas no lineales y procesamiento de soluciones.
Principales métodos:
- Difracción de rayos X monocristalino para la determinación estructural.
- Análisis de la función de distribución de pares (PDF) para revelar las distorsiones locales.
- Medición experimental y cálculos teóricos de la estructura de la banda (sX-LDA FLAPW) para las propiedades electrónicas.
- Mediciones ópticas no lineales (NLO) de segunda generación armónica (SHG).
Principales resultados:
- Identificación de cuatro tipos estructurales (alfa-LiAsSe2, beta-LiAsSe2, gamma-NaAsSe2, delta-NaAsSe2) con diferentes conformaciones de la cadena y el embalaje.
- Observación de una amplia gama de brechas de banda directas (1.11 eV a 2.23 eV) dependiendo de la composición.
- Gamma-NaAsSe2 exhibe una respuesta de segunda generación armónica (SHG) de NLO muy grande (337.9 pm / V), la más alta reportada para brechas de banda > 1.0 eV.
- Los materiales AAsSe2 demuestran solubilidad en disolventes comunes, lo que facilita el procesamiento de la solución.
Conclusiones:
- Los compuestos AAsSe2 representan una nueva clase de semiconductores polares de banda directa con propiedades sintonizables.
- Las propiedades estructurales y electrónicas están fuertemente influenciadas por el tipo de metal alcalino y la estequiometría.
- Gamma-NaAsSe2 es un material muy prometedor para aplicaciones de NLO debido a su significativa respuesta SHG.
- La solubilidad de estos materiales abre caminos para técnicas de fabricación basadas en soluciones rentables.
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