Solutions alternatives pour le filtrage des couleurs d'un capteur d'images numériques en technologie CMOS

Les capteurs d images numériques sont de plus en plus présents dans notre vie quotidienne : caméra pour téléphone portable, webcams etc. Cet énorme marché suit la tendance d une augmentation de la résolution tout en gardant une taille de capteur restreinte, augmentant ainsi le problème de la collection de la lumière au sein du pixel. Dans les capteurs d images CMOS, une solution serait de minimiser la distance entre les filtres colorés et la photodiode, ce qui implique que les filtres colorés puissent supporter un budget thermique au dessus de 500C. Dans cette étude, nous avons investigué expérimentalement des filtres colorés minéraux en transmission qui ont été élaboré par dépôt MOCVD. Les avantages principaux de ces derniers demeurent leur épaisseur (< 1 m ou presque), le budget thermique qu ils peuvent supporter ( au-delà de 500C) et la résistance vis-à-vis du recuit RH5.Digital image sensors are more and more present in every day of life: camera phones, webcams etc. This big market follows a main trend which is higher resolution while keeping small sensors, emphasizing the problem of light collection inside the pixel. ln Complementary Metal Oxide Semiconductor (CM OS) image sensors, a solution wou Id be to minimize the distance between the colour filters and the photodiode, what implies that colour filters could support a thermal process above 5OOC.ln this study, we investigate experimentally inorganic transmission colour filters using thin films prepared by MOCVD (Metal Organic Chemical Va pour Deposition). The main advantages of these filters remain their thickness llJm or almost), the annealing temperatu.re they can support (over 5OOc) and the resistance to the RHS annealing.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Efficient upconversion in Er3+ doped Y2O3/Si thin film deposited by aerosol UV-assisted MOCVD process

International audienc

Efficient green and red up-conversion emissions in Er/Yb co-doped TiO 2 nanopowders prepared by hydrothermal-assisted sol–gel process

International audienc

Effet de l'humidité du gaz vecteur et de l'assistance UV dans le procédé aérosol CVD pour l'élaboration de couches mines fluorescentes dopées terre rare

Le développement de couches minces dopées terres rares a suscité un regain d'intérêt au cours des dernières années. Dans ce mémoire nous présentons l'élaboration des couches minces d'yttria (Y2O3), d'alumine (Al2O3) et les couches mixtes Y2O3-Al2O3 dopées erbium. La technique utilisée est le procédé de dépôt chimique en phase vapeur à partir de précurseurs organométallique (MOCVD) assisté par aérosol. Un dispositif d'irradiation UV est appliqué afin d'assister le processus de réaction avec une modification de l'hygrométrie de l'air vecteur. Les meilleures propriétés sont obtenues pour les couches déposées sous une forte humidité de l'air vecteur et avec l'assistance UV. Dans ces conditions les couches d'yttria présentent une faible vitesse de croissance, une faible contamination organique et une bonne cristallinité dans la phase cubique de l'yttria. Plusieurs phénomènes d'Up-conversion ont été mis en évidence dans les spectres de fluorescence visible de l'erbium dans l'yttria. Une durée de vie du niveau 4I13/2 de l'erbium de 3.07 ms a été mesurée pour ce matériau après recuit à 800C. Cette valeur est supérieure à celle obtenue pour l'échantillon déposé sous une faible humidité de l'air et sans l'assistance UV après recuit à 1000C. Les couches d'alumine déposées dans les conditions optimales présentent des vitesses de croissance élevées et se caractérisent par une grande stabilité thermique, permettant l'élimination complète des impuretés tout en restant amorphe. Enfin, l'étude du système Y2O3-Al2O3 montre que les conditions de dépôt jouent un rôle important sur la composition et les propriétés physico-chimiques des dépôts.The development of rare earth-doped thin film has gained interest over these last few years. In this report we present the elaboration of erbium-doped yttria (Y2O3), alumina (Al2O3) and yttria-alumina (Y2O3-Al2O3) films. The technique used is aerosol assisted chemical vapor deposition processes with metalorganic precursors (MOCVD). A UV-irradiation device is applied to assist the reaction process with a modification in the air humidity of the carrier gas. The best properties are obtained on thin films grown under high air humidity and with UV-assistance. Under such deposition conditions the yttria films present a low growth rate, low organic contamination and higher crystallisation degree in the yttria cubic structure. Several up-conversion phenomena are point out in the visible fluorescence spectra of the erbium ion in yttria. A lifetime of the 4I13/2 Er3+ level of 3.07 ms was found in this material after annealing at 800C. This value is higher than that obtained for the sample deposited under low air humidity and without UV assistance after annealing at 1000C. Alumina film deposited under optimal conditions show high growth rate and was a high thermal stability; allow the complete elimination of impurities while remaining amorphous. At last, the results of system Y2O3-Al2O3 indicates that deposition conditions play an important role on the composition and physicochemical properties of films.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Magnesium-doped Cuprous Oxide (Mg:Cu2O) thin films as a transparent p-type semiconductor oxide

Oxide electronics is an important emerging area, notably for the development of transparent thin film transistors (TFTs) and other complex electronic circuits. The successful application of n-type oxides to TFTs has motivated the interest in p-type oxide based semiconductors, also to be applied to TFTs or to complementary metal-oxide semiconductor (CMOS) technology. However, until now there is a lack of p-type oxide semiconductors with performance similar to that of n-type oxide. Among the different metallic oxides, Cu (I)-based oxides exhibit one of the lowest ionic character. These compounds are therefore one of the most promising candidates as p-type transparent semiconductors.Nevertheless, the band gap of 2,17eV is modest for transparent electronics applications, since the transmittance of Cu2O films is low on the visible part of the light spectrum. The incorporation of cations with large radii than Cu has been proposed as a way to achieve a higher band gap, by diminishing of three-dimensional Cu-Cu interactions, only possible with larger cations than Cu+. Therefore, cation doped Cu2O thin films were grown by metal-organic chemical vapor deposition (MOCVD). The three doping elements studied (Sr2+, Sn2+ and La3+) were selected having in account theoretical predictions for the band structure and the deposition conditions of Cu2O. The study focus on thin films growth optimization combined with electronic transport analysis and optical transmittance measurements.2010-0004/000

In Situ Ellipsometry Study of the Early Stage of ZnO Atomic Layer Deposition on In 0.53 Ga 0.47 As

International audienc

Élaboration, caractérisation et propriétés physiques de couches minces d'alliages ternaires de type "Mictamict" (métal de transition-métalloïde-O ou N)

Des couches minces de composition TI-Si-O, Ru-Si-O et Ir-Si-O ont été obtenues par un procédé d'aérosol CVD à pression ambiante. Ces alliages, aussi appelés Mictamict, sont caractérisés par un mélange de deux composés normalement immiscibles. Après dépôt, les couches sont lisses et uniformes et amorphes en diffraction des rayons X. Pour l'alliage Ti-Si-O, des recuits à des températures jusqu'à 950C provoquent la formation de nanograins de Ti02 anatase immergés dans uen matrice de Si02 amorphe. Pour le système Ru-Si-O, les recuits conduisnet à une séparation de phase avec la croissance de Ru02 en surface. La forme des grains dépend de l'atmosphère du recuit. Les mesures des résistivités électriques montrent un comportement de pseudo semiconducteursThin films of Ti-Si-O, Ru-Si-O and Ir-Si-O were producted by an aerosol CVD process at ambient pressure. These also called Mictamict alloys are characterized by the mixture of tow usual Y unmixable compounds. As-deposited films are smooth and uniform and X ray amorphous. For the Ti-Si-O alloys, thermal annealing at temperatures up to S0oC induce the growth of Ti02 anatse nanograins embedded in an amorphous Si02 matrix. For the Ru-Si-O alloys, thermal annealing leads to a phase separation with the growth of Ru02 at the surface. The form of the grains depends on the annealing atmosphere. Electrical resistivity measurements show pseudo semiconducting behaviourGRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

The effect of rare earth (Er, Yb) element doping on the crystallization of Y2Ti2O7 pyrochlore nanoparticles developed by hydrothermal-assisted-sol-gel method

International audienc

Cation-doped Cu2O as a transparent p-type semiconducting oxide with enhanced performances: A comparison between strontium and magnesium incorporation

In the group of semiconducting metallic oxides, cuprous oxide (Cu2O) presents promising electrical and manufacturing features for a variety of applications as p-type transparent material suitable in the domains of transparent electronics and photovoltaic cells. However Cu2O suffers from optical and electrical limitations, due to a relatively small bandgap of 2.17 eV and a fairly high resistivity (> 102 Ω.cm) in intrinsic thin films at room temperature. In this work, we successfully doped Cu2O thin films with different divalent cations, namely Sr and Mg, by metal-organic chemical vapour deposition. We compared the effects of each element on crystallographic structure, films morphology, electronic transport and optical transmittance. In both cases, the presence of the cation contributed to a higher stability of the Cu2O phase, reducing the appearance of CuO parasitic phase. Nevertheless, a SrCO3 phase was detected in the Sr doped system. In terms of electrical properties, the incorporation of Sr, up to 16%, reduced the resistivity down to 1Ω.cm, with a mobility of 16 cm2.V-1.s-1. Moreover, the incorporation of strontium also leads to the emergence of a with a deep acceptor level located around EA = 278 ± 21 meV above the top of the valence band. The concentration of this deep acceptor level, attributed to simple copper vacancies, drastically increases with the strontium content, due to a decrease of its formation energy. The effect on optical transmittance could not be detected. The Mg-doped Cu2O thin films were monophasic and showed a higher resistivity of 6.6 Ω.cm at an Mg concentration of 17%, due to the lower mobility, 1 cm2.V-1.s-1. Although, the presence of this dopant contributes for the highest charge-carrier density observed in this work, up to 8x1017 cm-3. As in the Sr case, this can be explained by a simple copper vacancy doping mechanism assisted by cation incorporation. Additionally, a slight increase of transparency is observed when compared to intrinsic Cu2O. The control of carrier concentration and mobility values by dopant concentration, as well as the improvements in phase stability and transparency are key factors for the application of this versatile p-type oxide in transparent electronics and solar cells applications