Morphological, structural, optical, and electrical study of nanostructured thin films: Charge transport mechanism of p-type Co3O4

Morphological, structural, optical, and electrical study of nanostructured thin films: Charge transport mechanism of p-type Co3O

In- and out-plane transport properties of chemical vapor deposited TiO2 anatase films

Due to their polymorphism, TiO2 films are quintessential components of state-of-the-art functional materials and devices for various applications from dynamic random access memory to solar water splitting. However, contrary to other semiconductors/dielectric materials, the relationship between structural/morphological and electrical properties at the nano and microscales remains unclear. In this context, the morphological characteristics of TiO2 films obtained by metal–organic chemical vapor deposition (MOCVD) and plasma-enhanced chemical vapor deposition (PECVD), the latter including nitrogen doping, are investigated and they are linked to their in- and out-plane electrical properties. A transition from dense to tree-like columnar morphology is observed for the MOCVD films with increasing deposition temperature. It results in the decrease in grain size and the increase in porosity and disorder, and subsequently, it leads to the decrease in lateral carrier mobility. The increase in nitrogen amount in the PECVD films enhances the disorder in their pillar-like columnar morphology along with a slight increase in density. A similar behavior is observed for the out-plane current between the low temperature MOCVD films and the undoped PECVD ones. The pillar-like structure of the latter presents a lower in-plane resistivity than the low temperature MOCVD films, whereas the out-plane resistivity is lower. The tree-like columnar structure exhibits poor in- and out-plane conductivity properties, whereas pillar-like and dense TiO2 exhibits similar in- and out-plane conductivities even if their morphologies are noticeably different

Mesures à l'échelle sub-micronique des charges piégées dans les isolants : utilisation de méthodes dérivées de la Microscopie à Force Atomique

National audienceL'injection et l'accumulation de charges dans les isolants sont des phénomènes à l'origine de nombreuses défaillances. Pour comprendre ces phénomènes, des techniques de mesure de la charge d'espace ont été développées avec succès. Toutefois, leur résolution spatiale reste incompatible avec l'étude des films minces qui nous intéresse ici. Dans cet article nous proposons une nouvelle méthode de mesure de la charge d'espace dérivée de la microscopie à force atomique. Cette méthode, appelée EFDC (Electrostatic Force Distance Curve), permet la mesure directe de la force électrostatique induite par les charges piégées. Nous démontrons ici que cette technique est très sensible à la localisation latérale des charges piégées. La comparaison des résultats obtenus par EFDC avec ceux fournis plus classiquement par microscopie à sonde de Kelvin (KFM), montre que l'EFDC a une meilleure résolution latérale mais un caractère intrusif plus important que la méthode KFM

Towards 3D charge localization by a method derived from atomic force microscopy: the electrostatic force distance curve

International audienc

Atomic force microscopy developments for probing space charge at sub-micrometer scale in thin dielectric films

International audienc

Charge injection in thin dielectric layers by atomic force microscopy: influence of geometry and material work function of the AFM tip on the injection process

International audienc

Charges injection in thin layers by Atomic Force Microscopy : Influence of tip composition and geometry on injection processes

International audienc

Influence of dielectric layer thickness on charge injection, accumulation and transport phenomena in thin silicon oxynitride layers: a nanoscale study

International audienceCharge injection and retention in thin dielectric layers remain critical issues due to the great number of failure mechanisms they inflict. Achieving a better understanding and control of charge injection, trapping and transport phenomena in thin dielectric films is of high priority aiming at increasing lifetime and improving reliability of dielectric parts in electronic and electrical devices. Thermal silica is an excellent dielectric but for many of the current technological developments more flexible processes are required for synthesizing high quality dielectric materials such as amorphous silicon oxynitride layers using plasma methods. In this article, the studied dielectric layers are plasma deposited SiOxNy. Independently on the layer thickness, they are structurally identical: optically transparent, having the same refractive index, equal to the one of thermal silica. Influence of the dielectric film thickness on charging phenomena in such layers is investigated at nanoscale using Kelvin Probe Force Microscopy (KPFM) and Conductive Atomic Force Microscopy (C-AFM). The main effect of the dielectric film thickness variation concerns the charge flow in the layer during the charge injection step. According to the SiOxNy layer thickness two distinct trends of the measured surface potential and current are found, thus defining ultrathin (up to 15 nm thickness) and thin (15 nm-150 nm thickness) layers. Nevertheless, analyses of KPFM surface potential measurements associated with results from Finite Element Modelling of the structures show that the dielectric layer thickness has weak influence on the amount of injected charge and on the decay dynamics, meaning that pretty homogeneous layers can be processed. The charge penetration depth in such dielectric layers is evaluated to 10 nm regardless the dielectric thickness

Utilisation des courbes de force pour l'étude à l'échelle nanométrique des charges piégées dans les diélectriques en couches minces

International audienc

Dispersion et fiabilité technologique des micro-commutateurs capacitifs RF

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