Spatial Atomic Layer Deposition (SALD), an emerging tool for energy materials. Application to new-generation photovoltaic devices and transparent conductive materials

Muñoz‐Rojas, David; Nguyễn, Việt Hương; Huerta, César Masse de la; Aghazadehchors, Sara; Jiménez, Carmen; Bellet, Daniel

doi:10.1016/j.crhy.2017.09.004

Cited by 81 publications

(72 citation statements)

References 49 publications

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“…As reported previously, the atmospheric ('open-air') deposition of Al 2 O 3 using the highly pyrophoric precursor TMA, can be challenging to reproduce [56]. The ambient oxygen and water in the air (humid conditions) can act as an additional oxygen source that can increase growth rates [57]. Human error in adjusting the reactor head spacing can lead to an overmixing of the precursors (AP-CVD) and deposition with high rates [5].…”

Section: Film Nucleation and Growthmentioning

confidence: 99%

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

et al. 2020

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Atmospheric pressure-spatial atomic layer deposition (AP-SALD) is a promising open-air deposition technique for high-throughput manufacturing of nanoscale films, yet the nucleation and property evolution in these films has not been studied in detail. In this work, in situ reflectance spectroscopy was implemented in an AP-SALD system to measure the properties of Zinc oxide (ZnO) and Aluminum oxide (Al 2 O 3 ) films during their deposition. For the first time, this revealed a substrate nucleation period for this technique, where the length of the nucleation time was sensitive to the deposition parameters. The in situ characterization of thickness showed that varying the deposition parameters can achieve a wide range of growth rates (0.1-3 nm/cycle), and the evolution of optical properties throughout film growth was observed. For ZnO, the initial bandgap increased when deposited at lower temperatures and subsequently decreased as the film thickness increased. Similarly, for Al 2 O 3 the refractive index was lower for films deposited at a lower temperature and subsequently increased as the film thickness increased. Notably, where other implementations of reflectance spectroscopy require previous knowledge of the film's optical properties to fit the spectra to optical dispersion models, the approach developed here utilizes a large range of initial guesses that are inputted into a Levenberg-Marquardt fitting algorithm in parallel to accurately determine both the film thickness and complex refractive index.

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Section: Film Nucleation and Growthmentioning

confidence: 99%

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

et al. 2020

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“…[28] Therefore, several advancements are needed in order for this technology to allow fabrication on organic substrates. Therefore, all of the considered steps are designed and applicable for large-area production on silicon.…”

Section: Wwwadvelectronicmatdementioning

confidence: 99%

Short‐Channel Vertical Organic Field‐Effect Transistors with High On/Off Ratios

Doǧan

Verbeek

Kronemeijer

et al. 2019

Adv Elect Materials

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requires a large transistor width and a short transistor channel length in order to excel in the mentioned attributes. [7][8][9][10] From the architectural perspective, in an integrated pixelated device, transistors should also have small footprints so that light-emitting/-sensing devices can occupy larger areas on each pixel. Yet for planar OFETs, the device area increases with the width and decreasing the channel length demands high-resolution patterning. A vertical geometry allows reduced area requirements by employing a submicrometer thick organic film as the transistor channel. [11,12] However, when the channel length of an OFET approaches the 100 nm regime, high electric fields result in large bulk current densities that cannot be modulated efficiently via a gate-field. [13][14][15] This phenomenon is known as the shortchannel effect and it restricts further improvement of vertical OFETs (VOFETs).In this report, a novel VOFET geometry is demonstrated addressing the short-channel effect, in particular by suppressing the undesired bulk current. It is based on a gate electrode consisting of massively parallel highly doped silicon nanopillars (Figure 1). Crucially different from other VOFETs, an insulating layer is deposited on top of the bottom contact in order to force injection of the charge carriers only from the sides of the bottom metal, and current flow within a thin layer close to the gate dielectric, minimizing space-charge limited current through the bulk semiconductor. Thanks to this unique geometry, ON/OFF ratios up to 10 6 can be realized, i.e., at least three orders of magnitude larger than in previously reported short-channel (100 nm) VOFETs. [11,15] In order to fabricate the nanopillars with a high areal density (≈10 6 pillars mm −2 ), optical resist dots (100 nm radius) arranged in a hexagonal lattice (250 nm lattice constant) are created using displacement Talbot lithography (DTL). It allows for fast wafer-scale patterning. [16] This resist dot pattern acts as an etch mask during etching of about 300 nm into the underlying silicon. Since the silicon is highly doped p-type (resistivity of 0.010-0.025 Ω cm), it can be directly used as a massively parallel nanopillar gate electrode for a single device (≈7 × 10 5 pillars per device of total size 0.7 µm 2 ). In our experiments, we use bulk silicon wafers, but silicon-on-insulator wafers can be used in order to electrically separate individual many-pillar devices. A stoichiometric low-pressure chemical-vapor-deposited (LPCVD) 45 nm silicon nitride (Si 3 N 4 ) isolates these A unique vertical organic field-effect transistor structure in which highly doped silicon nanopillars are utilized as a gate electrode is demonstrated. An additional dielectric layer, partly covering the source, suppresses bulk conduction and lowers the OFF current. Using a semiconducting polymer as active channel material, short-channel (100 nm) transistors with ON/OFF current ratios up to 10 6 are realized. The electronic behavior is explained using space-charge and contact-lim...

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“…It has the ability to control the film thickness in the atomic scale range and produce uniform and pinhole‐free films at modest temperatures (e.g., 80–200 °C) . By adjusting the conditions to allow precursor mixing in the gas phase, CVD can also be performed in the same system . AP‐CVD conditions are attractive for device manufacturing, as it has been shown that higher deposition rates are obtained, while still producing smooth, pinhole‐free, conformal films with thicknesses proportional to the number of cycles .…”

Section: Introductionmentioning

confidence: 99%

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

Alshehri

Mistry

Nguyễn

et al. 2018

Adv Funct Materials

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A quantum-tunneling metal-insulator-metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP-CVD) for the first time. This scalable method is used to produce MIM diodes with high-quality, pinhole-free Al 2 O 3 films more rapidly than by conventional vacuum-based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum-enabled devices. In fact, the MIM diodes fabricated by AP-CVD show a lower effective barrier height (2.20 eV) at the electrodeinsulator interface than those fabricated by conventional plasma-enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero-bias resistance, and better asymmetry of 107.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201805533. dielectric layer sandwiched between two metal contacts. MIM diodes are capable of rectification in the high frequency range due to a femtosecond quantum-tunneling electron transport mechanism through the insulator, making them attractive for applications in solar rectennas, [1] infrared detectors, [2,3] and wireless power transmission. [4] However, the insulator layer in the MIM stack, which plays a crucial role in determining the diode performance, [5] is typically deposited using vacuum-based methods, such as sputtering, [6] anodic oxidation of sputtered films, [7] electron beam deposition, [8] and especially atomic layer deposition (ALD), [9] which is commonly used due to its ability to deposit nanoscale films with high accuracy and uniformity. High-throughput fabrication of MIM diodes is limited by slow deposition rates and the need for a vacuum environment. Scalable techniques are therefore needed for depositing nanoscale films for the next generation of integrated quantum devices. Some deposition processes have been introduced to fabricate thin films at atmospheric pressure for nanoelectronic devices that utilize quantum phenomena. Thermal and anodic oxidation, for example, have been used to grow thin CrO x and Nb 2 O 5 films on Cr and Nb layers for MIM diodes [7,10] ; atmospheric pressure metal organic vapor phase epitaxial growth (AP-MOVPE), or atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD), has been used to fabricate InGaAsP multiquantum-well structures for optical devices [11] ; the Langmuir Blodgett technique was used to deposit a ZnO film for a MIM diode [12] ; and a chemical vapor deposition (CVD) furnace operated at atmospheric pressure has been used to deposit a TiO 2 film in a tunneling transistor. [13] The need for high temperatures, specific metal films for oxidation, and complex compound precursors in these techniques, as well as challenges in reproducibility, highlight the need for new methods to reliably deposit enabling films for cost-effective quantum devices. Recently, atmospheric pressure spatial atomic layer deposition (AP-SALD) systems have been utilized to grow uniform films for different applications including solar cells...

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Spatial Atomic Layer Deposition (SALD), an emerging tool for energy materials. Application to new-generation photovoltaic devices and transparent conductive materials

Cited by 81 publications

References 49 publications

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

Short‐Channel Vertical Organic Field‐Effect Transistors with High On/Off Ratios

Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

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