Atomic Layer Deposited Aluminum Oxide Research Articles

Continuous-Flow Electrophoresis of DNA and Proteins in a Two-Dimensional Capillary-Well Sieve.

Continuous-flow electrophoresis of macromolecules is demonstrated using an integrated capillary-well sieve arranged into a two-dimensional anisotropic array on silicon. The periodic array features thousands of entropic barriers, each resulting from an abrupt interface between a 2 μm deep well (channel) and a 70 nm capillary. These entropic barriers owing to two-dimensional confinement within the capillaries are vastly steep in relation to those arising from slits featuring one-dimensional confinement. Thus, the sieving mechanisms can sustain relatively large electric field strengths over a relatively small array area. The sieve rapidly sorts anionic macromolecules, including DNA chains and proteins in native or denatured states, into distinct trajectories according to size or charge under electric field vectors orthogonally applied. The baseline separation is achieved in less than 1 min within a horizontal migration length of ∼1.5 mm. The capillaries are self-enclosed conduits in cylindrical profile featuring a uniform diameter and realized through an approach that avoids advanced patterning techniques. The approach exploits a thermal reflow of a layer of doped glass for shape transformation into cylindrical capillaries and for controllably shrinking the capillary diameter. Lastly, atomic layer deposition of alumina is introduced for the first time to fine-tune the capillary diameter as well as to neutralize the surface charge, thereby suppressing undesired electroosmotic flows.

Investigation of the fracture of very thin amorphous alumina film during spherical nanoindentation

Thin amorphous alumina layers (10 to 40nm thick) are processed on sputtered aluminum thin film (500nm) by atomic layer deposition (ALD) at low temperature (85°C). Global methodology combining quantitative experimental observations of fracture and numerical modeling is proposed to obtain the fracture strength of ALD thin film on Al layer. First, mechanical properties of the multilayer specimen are characterized by Berkovich nanoindentation, then fracture of ALD alumina is studied through spherical indentation with various tip radius. Spherical indentation load driven-displacement curves display a plateau (pop-in) at a critical load and critical indentation depth. A statistical approach is used to determine pertinent/fracture parameters from pop-in displacement. Careful SEM and AFM observations of indentation imprint exhibit circumferential cracking in agreement with the assumption that the pop-in event is predominantly controlled by the fracture of the oxide layer on the soft Al film. Finally, a numerical model calibrated with experimental results is used in order to predict both the mechanical response prior to the oxide fracture and a value of fracture strength for ALD alumina thin films.

Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density Dit(E) and the total interface charge Qtot. Furthermore, the bonding configuration variation of the AlOx films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlOx tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlOx layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

Numerical investigation of metal–semiconductor–insulator–semiconductor passivated hole contacts based on atomic layer deposited AlOx

Excellent c-Si tunnel layer surface passivation has been obtained recently in our lab, using atomic layer deposited aluminium oxide (ALD AlOx) in the tunnel layer regime of 0.9 to 1.5 nm, investigated to be applied for contact passivation. Using the correspondingly measured interface properties, this paper compares the theoretical collection efficiency of a conventional metal–semiconductor (MS) contact on diffused p+ Si to a metal–semiconductor–insulator–semiconductor (MSIS) contact on diffused p+ Si or on undoped n-type c-Si. The influences of (1) the tunnel layer passivation quality at the tunnel oxide interface (Qf and Dit), (2) the tunnel layer thickness and the electron and hole tunnelling mass, (3) the tunnel oxide material, and (4) the semiconductor capping layer material properties are investigated numerically by evaluation of solar cell efficiency, open-circuit voltage, and fill factor.

Impacts of light illumination on monocrystalline silicon surfaces passivated by atomic layer deposited Al2O3 capped with plasma-enhanced chemical vapor deposited SiNx

In this work, we investigate the impact of light illumination on crystalline silicon surfaces passivated with inline atomic layer deposited aluminum oxide capped with plasma-enhanced chemical vapor deposited silicon nitride. It is found that, for dedicated n-type lifetime samples under illumination, there is no light induced degradation (LID) but enhanced passivation. The lifetime increase happened with a much faster speed compared to the lifetime decay during dark storage, resulting in the overall lifetime enhancement for actual field application scenarios (sunshine during the day and darkness during the night). In addition, it was found that the lifetime enhancement is spectrally dependent and mainly associated with the visible part of the solar spectrum. Hence, it has negligible impact for such interfaces applied on the rear of the solar cells, for example p-type aluminum local back surface field (Al-LBSF) cells.

Impurity gettering effect of atomic layer deposited aluminium oxide films on silicon wafers

We present experimental evidence for the impurity gettering effect of atomic layer deposited aluminium oxide (Al2O3) films on silicon wafers, during typical surface passivation activation at 425 °C. Iron was used as a model impurity in silicon to study the gettering effects. Dissolved iron concentrations were determined by carrier lifetime measurements, allowing the iron loss kinetics in silicon wafers with Al2O3 coatings to be monitored during annealing. The redistribution of iron to the surface layers and the sub-surface regions was examined by secondary ion mass spectrometry depth profiling. The results show that the atomic layer deposited Al2O3 films generate a strong gettering effect, removing 50% of the iron after 30 min at 425 °C for a 160-μm thick silicon wafer. The iron reduction process is largely diffusion-limited in the initial stages. The gettering effect is caused by the accumulation of iron at the Al2O3/Si interface.

Plasma-assisted ALD to functionalize PET: towards new generation flexible gadgets

We report a novel, efficient, plasma-enabled technique to significantly enhance the protective barrier properties of alumina films deposited on thin polyethylene terephthalate (PET), which is a potential candidate for use in next-generation flexible gadgets and various portable equipment. Capacitively coupled oxygen plasma pretreatment was proposed and successfully tested to drastically reduce the water vapour transmission rate and water contact angle. The influence of the deposition temperature and in-chamber cooling of the prepared alumina layers on the protective characteristics of coated PET was also studied. We have found that higher deposition temperature improves the water vapour barrier performance of PET coated with atomic layer deposition alumina films. To keep the temperatures at a minimum, oxygen plasma could be efficiently employed to treat PET and thus ensure a strong interfacial interaction between the alumina and PET surfaces. With the assistance of the oxygen plasma treatment technique, alumina coating reduced the water vapour transmission rate of PET to less than 1 mg × m−2 × day−1 without a long post-process cooling. This technique may be suitable for application of virtually any ceramic films at low temperature onto various polymer substrates, which is urgently required for present-day flexible gadgets and other portable equipment including those working in aggressive environments.

Atomic layer deposition surface functionalized biochar for adsorption of organic pollutants: improved hydrophilia and adsorption capacity

Atomic layer deposition (ALD) thin film coating was applied to improve the hydrophilia of biochar derived from black willow. 2 (2Al, 0.82 wt% Al2O3), 5 (5Al, 1.40 wt% Al2O3), and 10 (10Al, 2.36 wt% Al2O3) cycles of alumina ALD were applied. The biochars were characterized by inductively coupled plasma–atomic emission spectroscopy, nitrogen adsorption and desorption, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorbents were utilized for the removal of methylene blue (MB) from an aqueous solution to evaluate their adsorption capacities. The 5Al biochar showed the highest adsorption capacity, compared to the uncoated biochar and other Al2O3 coated biochars, due to its improved hydrophilia. The amount of MB adsorbed onto the 5Al biochar was almost three times that adsorbed onto the uncoated biochar during the first hour of adsorption experiments. Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms. The data fit well with the Langmuir isotherm, and the maximum adsorption capacities were found to be 26.8 and 35.0 mg/g at 25 °C for the uncoated biochar and 5Al biochar, respectively. The adsorbed MB amount per square meter achieved 1.3 mg/m2 onto the 5Al biochar, and it was twice the amount on the uncoated biochar. The experimental data were analyzed by pseudo-first-order and pseudo-second-order kinetics models of adsorption. The pseudo-second-order model better describes adsorption kinetic data for the uncoated biochar and 5Al biochar than the pseudo-first-order model does.

Characterization and prevention of humidity related degradation of atomic layer deposited Al2O3

Atomic layer deposited aluminum oxide (ALD-Al2O3) is a dielectric material, which is widely used in organic light emitting diodes in order to prevent their organic layers from humidity related degradation. Unfortunately, there are strong hints that in some cases, ALD-Al2O3 itself is suffering from humidity related degradation. Especially, high temperature and high humidity seem to enhance ALD-Al2O3 degradation strongly. For this reason, the degradation behavior of ALD-Al2O3 films at high temperature and high humidity was investigated in detail and a way to prevent it from degradation was searched. The degradation behavior is analyzed in the first part of this paper. Using infrared absorbance measurements and X-ray diffraction, boehmite (γ-AlOOH) was identified as a degradation product. In the second part of the paper, it is shown that ALD-Al2O3 films can be effectively protected from degradation using a silicon oxide capping. The deposition of very small amounts of silicon in a molecular beam epitaxy system and an X-ray photoelectron spectroscopy investigation of the chemical bonding between the silicon and the ALD-Al2O3 surface led to the conclusion that a silicon termination of the ALD-Al2O3 surface (Al*-O-SiOx) is able to stop humidity related degradation of the underlying ALD-Al2O3 films. The third part of the paper shows that the protection mechanism of the silicon termination is probably due to the strong tendency of silicic acid to resilificate exposed ALD-Al2O3 surfaces. The protective effect of a simple silicon source on an ALD-Al2O3 surface is shown exemplary and the related chemical reactions are presented.

High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells

Front metal contact induced recombination and resistance are major efficiency limiting factors of large-area screen-printed n-type front junction Si solar cells with homogeneous emitter and tunnel oxide passivated back contact (TOPCON). This paper shows the development of a selective boron emitter (p+/p++) formed by a screen-printed resist masking and wet chemical etch-back process, which first grows a porous Si layer and subsequently removes it. Various wet-chemical solutions for forming porous Si layer are investigated. An industrial compatible process with sodium nitrite (NaNO2) catalyst is developed to uniformly etch-back the ∼47 Ω/◻ atmospheric pressure chemical vapor deposited heavily doped boron emitter to ∼135 Ω/◻ by growing a 320 nm porous Si layer within 3 min and subsequently removing it. After etching back, the boron emitter was subjected to a thermal oxidation to lower the surface concentration and the emitter saturation current density J0e. Various etched-back emitters were evaluated by measuring J0e on symmetric test structures with atomic layer deposited aluminum oxide (Al2O3) passivation. Very low J0e of 21, 14, and 9 fA/cm2 were obtained for the 120, 150, and 180 Ω/◻ etched-back emitters, respectively. A solar cell with a selective emitter (65/180 Ω/◻) formed by this etch-back technology and with an Al/Ag contact on the front and TOPCON on the back gave an open-circuit voltage (Voc) of 682.8 mV and efficiency of 21.04% on n-type Czochralski Si wafer. This demonstrates the potential of this technology for next generation high-efficiency industrial n-type Si solar cells.

Effect of reactor pressure on the conformal coating inside porous substrates by atomic layer deposition

Atomic layer deposition (ALD) is renowned for its step coverage in porous substrates. Several emerging applications require a combination of this high step coverage with high throughput ALD, like spatial ALD. Often, high throughput ALD is performed at atmospheric pressure, and therefore, the effect of reactor pressure on the saturation dose is investigated. ALD inside porous substrates is governed by three key parameters: the reaction probability, the pore aspect ratio, and the precursor diffusion coefficient, of which the latter one contains the reactor pressure dependency. The effect of these parameters on the saturation dose is validated using Monte Carlo modeling, where the reactor pressure dependency is included through the mean free path. A reaction-limited and a diffusion-limited regime can be identified, and it is shown that for many realistic experimental conditions, even at low reactor pressures, the saturation dose is in the diffusion-limited regime. An expression for the pressure dependent saturation dose in the diffusion-limited regime is derived. For small pore diameters, the saturation dose is pressure independent, but for larger pores, higher saturation doses are required for atmospheric reactor pressures than for low reactor pressures. However, as high reactor pressures enable much higher precursor partial pressures than low reactor pressures, the resulting saturation times can be much shorter at atmospheric pressure than low pressure. Often, high surface area porous substrates will lead to supply limited conditions, and increased saturation times have to be taken into account. These results show that the atmospheric pressure ALD can be used for high throughput ALD inside porous substrates, as long as high precursor partial pressures and molar flows can be applied. This is experimentally demonstrated by a near 100% step coverage obtained by atmospheric spatial ALD of alumina in high aspect ratio pores.

Tris(dimethylamido)aluminum(III): An overlooked atomic layer deposition precursor

Aluminum oxide and aluminum nitride-containing films were grown by atomic layer deposition (ALD) and plasma-enhanced atomic layer deposition (PE-ALD) by employing an under-utilized tris(dimethylamido)aluminum(III) precursor. This compound has not been reported as a precursor for ALD of alumina previously, and has only been reported as an AlN precursor for a thermal process using ammonia as a coreagent. Thermogravimetric analysis demonstrates its excellent volatility and thermal stability, both of which are ideal characteristics for an ALD precursor. Aluminum oxide films were deposited thermally using water as a coreagent. By x-ray photoelectron spectroscopy, the films appeared nearly pristine with only adventitious carbon on the surface accumulated postdeposition that was easily removed with 2 min of Ar+ sputtering. The rest of the films contained a very low 1.4% impurity of carbon. Aluminum nitride films were attempted using the same aluminum precursor with nitrogen plasma as a coreagent; they contained large amounts of oxygen due to ambient exposure, possible oxidation during characterization, or the presence of incidental oxygen during the deposition of AlN, which allowed the formation of an aluminum oxynitride. Though the composition was not stoichiometrically AlN, the films also contained ∼1% carbon impurities, which is an improvement over many other AlN films reported, particularly those using TMA as a precursor. This precursor shows great promise for the deposition of low-impurity or impurity-free aluminum nitride by PE-ALD.

Band offsets and trap-related electron transitions at interfaces of (100)InAs with atomic-layer deposited Al2O3

Spectral analysis of optically excited currents in single-crystal (100)InAs/amorphous (a-)Al2O3/metal structures allows one to separate contributions stemming from the internal photoemission (IPE) of electrons into alumina and from the trapping-related displacement currents. IPE spectra suggest that the out-diffusion of In and, possibly, its incorporation in a-Al2O3 lead to the development of ≈0.4 eV wide conduction band (CB) tail states. The top of the InAs valence band is found at 3.45 ± 0.10 eV below the alumina CB bottom, i.e., at the same energy as at the GaAs/a-Al2O3 interface. This corresponds to the CB and the valence band offsets at the InAs/a-Al2O3 interface of 3.1 ± 0.1 eV and 2.5 ± 0.1 eV, respectively. However, atomic-layer deposition of alumina on InAs results in additional low-energy electron transitions with spectral thresholds in the range of 2.0–2.2 eV, which is close to the bandgap of AlAs. The latter suggests the interaction of As with Al, leading to an interlayer containing Al-As bonds providing a lower barrier for electron injection.

Wear behavior of annealed atomic layer deposited alumina

Atomic layer deposited (ALD) alumina is a promising candidate for use as a wear-resistant and protective coating in MEMS and other applications. While the tribological properties of ALD alumina may be affected by numerous factors related to processing, environment, and operating conditions, its wear behavior is neither quantified nor well understood. In this study, ALD alumina is annealed at different temperatures, then subjected to sliding wear testing in a humid air environment. Tribological properties appear to be heavily influenced by annealing temperature. Surprisingly, the wear rate decreased by about two orders of magnitude after annealing at 1000 ⁰C for 1 hour. This improvement in wear resistance was shown to be influenced by the formation of crystalline phases as annealing temperature increased.

Analysis and in situ observation of humidity dependent atomic layer deposited-Al2O3 degradation

The degradation of atomic layer deposited aluminum oxide (ALD-Al2O3) at high temperature and high humidity was investigated. The intrinsic hydroxyl concentration of as-deposited ALD-Al2O3 was evaluated using a temperature dependent deposition study and its impact on degradation behavior was analyzed. In addition, the degradation of ALD-Al2O3 was monitored in situ using a plate capacitor with ALD-Al2O3 as dielectric. A model for the ALD-Al2O3 degradation mechanism was proposed based on the penetration of water molecules into the ALD-Al2O3 and on the formation of aluminum hydroxide. Two parameters, delay-time (time till a change in capacitance occurs) and wetting speed (speed of molecular water penetration into the ALD-Al2O3), were extracted from the capacitance measurements in order to evaluate the dependence of ALD-Al2O3 degradation on temperature and humidity.

Passivation of all-angle black surfaces for silicon solar cells

Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles support the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells.

Anomalously high alumina atomic layer deposition growth per cycle during trimethylaluminum under-dosing conditions

Under nominal conditions for this study, alumina atomic layer deposition (ALD) using trimethylaluminum and water as precursors was found to give a growth-per-cycle (gpc) of 1.1 Å under saturating conditions. As either precursor dose is reduced, one expects to find a point where the gpc begins to drop from the self-saturating plateau to zero in a monotonically decreasing manner while thickness nonuniformity along the deposited film starts to increase. In this paper, the authors find anomalously high gpc values—more than twice our nominal value of 1.1 Å—during the transition to precursor under-dosing as the trimethylaluminium dose is reduced while the water dose is held constant. Unlike previous studies documenting abnormally high alumina ALD gpc, the authors find that film thickness remains spatially uniform in this region, up to the point where precursor depletion becomes significant, resulting in films with severe spatial gradients in the direction of precursor flow. A simple reaction mechanism is postulated to explain the observed gpc behavior.

Low-Overpotential Li-O2 Battery: An Application of Nanostructured Cathode Architecture By Atomic Layer Deposition

Li-O2 battery was first reported in 1996, and makes remarkable progress in the recent years with the improvement of technique and knowledge. It has also received significant attention during the past several years due to its extremely high theoretical energy density, which is about 10 times than the commercial Li-ion batteries and comparable with gasoline. However, its sluggish kinetics, which usually results large voltage polarization and low efficiency, hinders the practical applications in commercialized devices. It is generally accepted that various factors, such as the nature, morphology, and surface area of the catalysts, influence the electrochemical reactions in Li-O2 battery. Therefore, it has become an emerging topic to design efficient catalysts which could facilitate the electrochemical reactions. Carbonate-based electrolyte was widely applied in Li-O2 battery system. However, its instability under O2 is one of the major reasons of the poor performance reported previously. Ether-based electrolyte (e.g. TEGDME) is currently broadly employed to reduce the electrolyte decomposition and benefit the catalytic performance, due to the relatively stability under O2 and high potential. However, the decomposition is still observed, even at the charge potential as low as 3.5 V, which may result from reactions of the electrolyte with defect sites on the porous carbon surface. It is reasonable to expect that the electrolyte decomposition would be significantly reduced by a decrease in the surface defect sites. Our previous study reported a reduction in charge overpotential to 0.2 V by an alumina atomic layer deposition (ALD) on porous carbon surface which prevents electrolyte decomposition on carbon surface. By taking advantage of the difference in surface reaction rate, ALD technique can provide selectively deposition of the coating materials onto the targeted surface. Accordingly, the cathode based on the passivation layer architecture shows promising results for solving the charge overpotential problem by passivating the surface defect sites. Here we describe an approach based on a cathode architecture that has a protective ZnO coating passivation layer on a porous carbon substrate. Bulk ZnO has a direct band gap of 3.3 eV, much smaller than that of bulk Al2O3 (8.8 eV). ZnO ALD using alternating exposures to diethylzinc and water is well understood and provides conformal coatings. In addition, the growth rate of Pd is faster on the ZnO surface than the Al2O3 surface. All the above advantages make ZnO a promising material as the passivating layer on carbon. In this study, we demonstrated that a cathode architecture with uniformly dispersed palladium nanoparticles onto a ZnO-passivated porous carbon substrate prepared by ALD shows high electrochemical catalytic activity in Li-O2 battery. Transmission electron microscopy (TEM) showed discrete crystalline nanoparticles decorating the surface of the ZnO-passivated porous carbon support in which the size could be controlled in the range of 3–6 nm, depending on the number of Pd ALD cycles performed. X-ray absorption spectroscopy (XAS) at the Pd K-edge revealed that the carbon-supported Pd existed in a mixed phase of metallic palladium and palladium oxide. The ZnO-passivated layer effectively blocks the defect sites on the carbon surface, minimizing the electrolyte decomposition. As a result, this cathode architecture reduced the charge overpotential to almost 0 V, which is the lowest ever reported. The discharge products are characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the Pd loading on the electrochemical performance of the Li-O2 cell is also investigated. Our results not only show promising results for solving the charge overpotential problem, and provide the basis for future development of lithium-oxygen cathode materials that can be used to improve the efficiency and to extend cycle life.

ALD Coating of Selective Laser Melted 3-D Printed Stainless Steels

Selective laser melting (SLM), also known as 3-D printing or additive manufacturing process, has been developed for over 2 decades. This technique exhibits the capability to fabricate three-dimensional metal objects of complex geometries & structures from metal powders used in aerospace or medical orthopedics. This additive manufacturing technology has received a lot of attention, because various metals and metal alloys can now be processed to manufacture metal parts or structures, which includes the technologically important metals of stainless steel, cobalt chrome, titanium, tungsten and various other alloys. Typically SLM selectively melts thin layers of fine metal powder above each other by using a focused laser beam with high thermal energy on a substrate plate under argon atmosphere, resulting in production of almost full density metal or alloy parts. In this fashion successive layers of material are formed according to the computer edited 3-D-CAD design. Thereby, SLM could be applied to make functional end-use and geometrically complex products with cost-effect process especially in industry. Due to the geometrically complex form of the SLM manufactured structures, atomic layer deposition (ALD) is uniquely suitable to control the composition, thickness and conformability of thin films in the large scale and complex structures. In this study we report ALD coatings of Al2O3 of SLM stainless steel with the objective of providing corrosion protection by an alumina diffusion barrier and ALD ZrO2 coatings. During the course of this work we found the parts fabricated by 3-D printers tend to be porous and exhibit a rough texture. Figures 1 (a) show FE-SEM micrographs at progressively larger magnification of the surface of the 3-D printed stainless steel samples. As can be seen, the surface is very rough and contain many beads or spheres produced during the SLM manufacturing process, which is a direct result of the laser melting of the metal powder and rapid quenching. In order to reduce the surface roughness of the 3-D printed samples, electropolishing was used to smoothen and streamline the rough surface of the 3-D samples. After electropolishing, the surface of the 3-D printed samples is bright, clean and microscopically smooth and featureless. There are no beads or spheres remaining on the samples as shown in Figures 1 (b). We used SLM 316 stainless steel samples in a cross-flow ALD reactor with TMA and H2O vapor to attempt ALD coatings, while TDMA-Zr and H2O were used as precursors for ALD ZrO2. The analysis of the ALD Al2O3 and ZrO2 films revealed satisfactory chemisorption on the 3-D printed stainless steel surface. The ALD Al2O3 and ZrO2 films were uniformly grown on the 3-D printed stainless steel surface as shown in Figure 2. Figure 1

Evaluation of Different High Κ Materials for In situ Growth of Carbon Nanotubes

In this work we investigate the in situ growth of carbon nanotubes (CNTs) on different dielectric stacks for use in discrete field-effect transistor devices. While CNT growth is demonstrated on all stacks, only devices fabricated on atomic layer deposited aluminum oxide show sufficiently reliable gate dielectrics. Electrical burn pulses are applied to the devices to selectively remove undesired metallic CNTs in order to obtain proper transistor behavior with an on/off current ratio of five orders of magnitude.