{"id":62359,"date":"2008-11-01T00:00:00","date_gmt":"2008-11-01T00:00:00","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/caracterizacion-quimica-electronica-y-estructural-de-nitruros-de-metales-de-transicion\/"},"modified":"2008-11-01T00:00:00","modified_gmt":"2008-11-01T00:00:00","slug":"caracterizacion-quimica-electronica-y-estructural-de-nitruros-de-metales-de-transicion","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/quimica\/caracterizacion-quimica-electronica-y-estructural-de-nitruros-de-metales-de-transicion\/","title":{"rendered":"Caracterizacion quimica, electronica y estructural de nitruros de metales de transicion"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Cristina Navio Bernabeu <\/strong><\/h2>\n<p>La finalidad de la tesis ha sido la caracterizaci\u00f3n qu\u00edmica, electr\u00f3nica y estructural de nitruros de metales de transici\u00f3n, concretamente de cobre y hierro, con el objetivo inicial de poder construir uniones t\u00fanel magn\u00e9ticas (mtj), componentes esenciales de las memorias ram de los ordenadores (mrams).  los nitruros de cobre (cu3n) son materiales semiconductores cuyo gap var\u00eda entre 1 y 1.9 ev (seg\u00fan diferentes valores publicados en la literatura). Los estudios de difracci\u00f3n de rayos x han permitido determinar la epitaxialidad de pel\u00edculas ultradelgadas (desde 1 a 8 nm) de nitruros de cobre sobre fe (001) a temperatura ambiente y la estabilidad de estos compuestos a presi\u00f3n atmosf\u00e9rica. Gracias a los experimentos de fotoemisi\u00f3n (tanto de rayos x como de ultravioleta) se ha determinado la composici\u00f3n y la estructura electr\u00f3nica, en la que se pudo confirmar su car\u00e1cter semiconductor debido a la ausencia de estados en el nivel de fermi (el borde de la banda de Valencia est\u00e1 a 0.65 ev por debajo del ef). Se realizaron c\u00e1lculos de primeros principios utilizando el c\u00f3digo siesta en los que se predijo una curvatura de las bandas hacia arriba causada por la descompensaci\u00f3n en la densidad de estados (dos) por encima y debajo del nivel de fermi. Dicho fen\u00f3meno de curvatura de bandas fue observado tambi\u00e9n por fotoemisi\u00f3n y se obtuvo como resultado que el nivel de fermi se encuentra muy cerca de la banda de conducci\u00f3n, como ocurre con los semiconductores tipo n. Un aspecto importante y con bastante controversia en la literatura es la temperatura de descomposici\u00f3n del cu3n. El proceso comienza en la interfase de la pel\u00edcula con el sustrato a 440 k y es cin\u00e9tico.  en los nitruros de hierro hay que hacer dos divisiones: los crecidos a alta temperatura (alrededor de 700 k) y los crecidos a temperatura ambiente. En el primer caso, la fase obtenida es la de fe4n, material magn\u00e9tico y con un par\u00e1metro de red pr\u00e1cticamente id\u00e9ntico al del cu3n; de esta<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Caracterizacion quimica, electronica y estructural de nitruros de metales de transicion<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Caracterizacion quimica, electronica y estructural de nitruros de metales de transicion <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Cristina Navio Bernabeu <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Aut\u00f3noma de Madrid<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 11\/01\/2008<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Jes\u00fas Alvarez Alonso<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: enrique Garcia michel <\/li>\n<li> Soriano de arpe leonardo (vocal)<\/li>\n<li>Fernando Martin garcia (vocal)<\/li>\n<li> Pena jimenez Miguel Antonio (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Cristina Navio Bernabeu La finalidad de la tesis ha sido la caracterizaci\u00f3n qu\u00edmica, electr\u00f3nica y estructural de [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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