Papers by Keyword: Atomic Layer Deposition

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Authors: Kun Yuan Gao, Thomas Seyller, Konstantin V. Emtsev, Lothar Ley, Florin Ciobanu, Gerhard Pensl
Abstract: Atomic Layer Deposited Al2O3 films on hydrogen-terminated 6H-SiC(0001) were annealed in hydrogen atmosphere and characterized by admittance spectroscopy measurement and photoelectron spectroscopy (PES). The resultant density of interface trap (Dit) from admittance spectroscopy measurement is reduced near mid gap, but increases strongly towards the conduction band edge. Systematic PES measurements show that hydrogen annealing introduces Si4+ as a new component besides Si0 and Si+. Using different electron escape depths for photon electrons, depth profiling of Si in its different oxidation states was performed. The result indicates the formation of a top SiO2 layer and a rougher interfacial layer containing more Si+ and Si4+ which could be responsible for the strong increase of Dit just below the conduction band edge.
Authors: Matthias Müller, Sonja Sioncke, Annelies Delabie, Burkhard Beckhoff
Abstract: Thin films of high-k material are becoming more and more used for semiconductor devices. A further shrinking of the devices requires also a further reduction of the high-k film thickness. With this reduction of the high-k thickness down to just a few nanometers two technical challenges have to be addressed. The first one is the ALD process for the deposition of the high-k material. Usually the ALD process can be well controlled by tuning the number of process cycles. But it is theoretically predicted [1] that the growth-per-cycle of the first cycles can be different than the steady growth-per-cycle which is obtained for high cycle numbers. This effect is caused by a not fully covered initial surface during the first cycles. Only when the deposited material forms a closed surface and the surface probabilities are the same for each following cycle the deposition rate will be constant. The second challenge is that the electrical properties of thin films with a thickness of a few nanometers are significantly determined by the quality of the interface between the film and the substrate.
Authors: Yi Jia, Mang Yang, Wei Er Lu, Feng Ji, Chao Bo Li, You Tong Fang, Yang Xia
Abstract: Single and multilayer of Al2O3 and TiO2 were fabricated on anodized aluminum by atomic layer deposition. The effect of processing parameters on pore sealing and anti-corrosion property was studied. It is concluded that the micropores on anodized aluminum could be sealed by atomic layer deposition oxide films through SEM and staining experiments. The anti-corrosive property is affected mainly by the film thickness and process temperature. The acidic drip and salt spray test shows that the anti-corrosion property is enhanced as the film thickness increase. With the similar thickness, Al2O3/TiO2 multilayer film has the best anti-corrosion property, while the single Al2O3 layer appears the poorest. The complementary roles between two basic materials result in the enhanced application property.
Authors: Rwei Ching Chang, Hsi Ting Hou, Fa Ta Tsai, Pei Sin Jhu
Abstract: Atomic layer deposition (ALD) is utilized to grow high performance aluminum oxide (Al2O3) barrier films on flexible PET substrates, where the effects of precursor pulse time and deposition temperature on the film properties are also studied in this work. Significant differences are observed that the water vapor transmission rate of the PET substrate is largely improved by coating the Al2O3 barrier films. Further observations on the surface roughness, optical transmittance, adhesion, mechanical properties of the deposited films are also conducted. The results show that the Al2O3 film deposited with 10 msec precursor pulse time and 60°C deposition temperature behaves the best performance.
Authors: Markku Leskela, Emma Salmi, Mikko Ritala
Abstract: This paper reviews the use of Atomic Layer Deposition (ALD) in protective coatings. Because of the growth principle ALD allows the deposition of dense conformal films on substrates of different size and shape. Recently, ALD has received increasingly interest in deposition of protective coatings. In protective coatings oxides are the most common materials and especially Al, Ti, and Ta oxides have been applied. The use of nanolaminates enables improving the protection properties. Since ALD films are pinhole-free and often thin they are used to protect against moisture, radiation, out-gassing but not often against corrosion of metals. Very good moisture barriers are obtained with thin ALD oxide layers on polymers and cardboard. This property is also very attractive in encapsulation of OLEDs. In studies of energy technology materials protection of electrodes in Li-ion batteries, fuel cells and supercapacitors by ALD has been reported and significant improvement in the stability has been achieved. Yet another area is protection of silver jewelry from tarnishing by a thin oxide layer. In traditional corrosion protection of metals ALD films have proven to be useful in tailoring of interfaces and sealing of defects in coatings made by other techniques.
Authors: Siva Krishna Karuturi, Li Jun Liu, Liap Tat Su, Wen Bin Niu, Alfred Ling Yoong Tok
Abstract: Atomic layer deposition (ALD) technique shows superior application in the fabrication of TiO2 inverse opals (IO), compared with conventional infiltration methods. In the present report, TiO2 IO structures were infiltrated by ALD method in a continuous-flow and internally developed stop-flow process, respectively. The corresponding optical and optoelectrical properties of TiO2 IO structures were investigated. The prepared uniform IO structure of 288 nm was used as a photoanode for dye-sensitized solar cells. An efficiency of 2.22% was achieved, which was much higher than that of prepared by conventional solution-infiltration method. It is indicated that ALD method is an effective approach for fabricating TiO2 IO photoanode.
Authors: Dip K. Nandi, Shaibal K. Sarkar
Abstract: This work focuses on synthesis of molybdenum oxide (MoO3) by Atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo (CO)6] and ozone. In-situ growth characteresticswerestudied by Quartz Crystal Microbalance (QCM). ALD temperature window for this material lies between 165 to 175°C giving a maximum growth rate of 0.45 Å per ALD cycle. Negligible nucleation was found by QCM studyindicating a linear growth of the film. Effect of different oxidants on the growth rate is also studied.As-deposited film is amorphous in nature which converts to monoclinic-MoO3 after annealing as seen by taransmission electron microscopy.
Authors: Mika Vähä-Nissi, Terhi Hirvikorpi, Jenni Sievänen, Katriina Matilainen, Erkki Salo, Ali Harlin
Abstract: Biopolymers play still a relatively minor role in the packaging material markets. For this to grow further there are problems to be solved, such as inadequate barrier properties and moisture sensitivity. Atomic layer deposition (ALD) is one potential solution. Atomic layer deposition is a layer-by-layer thin film deposition process based on self-limiting gas-solid reactions. It is well suited for producing pinhole free barrier coatings uniform in thickness at relatively mild process conditions. The purpose of this presentation is to summarize our recent work done concerning atomic layer deposition of thin aluminum oxide layers onto biopolymers.
Authors: Adam Hinckley, Anthony Muscat
Abstract: Atomic layer deposition (ALD) was used to grow titanium nitride (TiN) on SiO2 with TiCl4 and N2H4. X-ray photoelectron spectroscopy (XPS) and ellipsometry were used to characterize film growth. A hydrogen-terminated Si (Si-H) surface was used as a reference to understand the reaction steps on SPM cleaned SiO2. The growth rate of TiN at 573 K doubled on Si-H compared to SiO2 because of the formation of Si-N bonds. When the temperature was raised to 623 K, O transferred from Ti to Si to form Si-N when exposed to N2H4. Oxygen and Ti could be removed at 623 K by TiCl4 producing volatile species. The added surface reactions reduce the Cl in the film below detection limits.
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