• Applied Chemistry for Engineering
• /
• v.33 no.4
• /
• pp.367-372
• /
• 2022

The effect of the addition of a polyvinylchloride (PVC) non-solvent to a PVC-tetrahydrofuran (THF) solution on the surface properties of the PVC thin film was analyzed. The non-solvents used were composed of alcohol-based and non-alcoholic ones. Surface morphologies of PVC thin films according to the addition of the non-solvent were compared. In addition, the hydrophobic properties relying on the surface characteristics were compared. The micro-bubbles generated in the preparation of PVC-THF solution affected the surface morphology of the thin film. In order to implement the normal surface physical properties of the coating thin film at the relatively high concentration of PVC-THF solution, the selection of appropriate drying method was required. When an alcohol-based non-solvent was added, a PVC thin film having a granular porous surface was obtained and exhibited super hydrophobic properties. The volume ratio of the PVC-THF solution to the non-solvent affects the surface shape of the coating thin film. The larger the amount of non-solvent was added, the more advantageous it was to form a super hydrophobic PVC thin film.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.318.1-318.1
• /
• 2013

Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2007.11a
• /
• pp.17.1-17.1
• /
• 2007

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1998.09a
• /
• pp.33-33
• /
• 1998

Invisible charged clusters are suggested to form in the gas phase and to become the growth unit in the thin film process. Similar suggestion had been made by Glasner el al. in the crystal growth of KBr and KCL in the solution where the lead ions were added. The charged cluster model, which was suggested in the diamond CVD process by our group, will be extended to the other thin film processes. It will be shown based on both the theoretical analysis and the experimental evidences that the charged clusters are formed in the gas phase and become the growth unit of the crystal in the thin film process.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.242-242
• /
• 2012

Transparent oxide semiconductors are increasingly becoming one of good candidates for high efficient channel materials of thin film transistors (TFTs) in large-area display industries. Compare to the conventional hydrogenated amorphous silicon channel layers, solution processed ZnO-TFTs can be simply fabricated at low temperature by just using a spin coating method without vacuum deposition, thus providing low manufacturing cost. Furthermore, solution based oxide TFT exhibits excellent transparency and enables to apply flexible devices. For this reason, this process has been attracting much attention as one fabrication method for oxide channel layer in thin-film transistors (TFTs). But, poor electrical characteristic of these solution based oxide materials still remains one of issuable problems due to oxygen vacancy formed by breaking weak chemical bonds during fabrication. These electrical properties are expected due to the generation of a large number of conducting carriers, resulting in huge electron scattering effect. Therefore, we study a novel technique to effectively improve the electron mobility by applying environmental annealing treatments with various gases to the solution based Li-doped ZnO TFTs. This technique was systematically designed to vary a different lithium ratio in order to confirm the electrical tendency of Li-doped ZnO TFTs. The observations of Scanning Electron Microscopy, Atomic Force Microscopy, and X-ray Photoelectron Spectroscopy were performed to investigate structural properties and elemental composition of our samples. In addition, I-V characteristics were carried out by using Keithley 4,200-Semiconductor Characterization System (4,200-SCS) with 4-probe system.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.5
• /
• pp.1473-1476
• /
• 2013

Solution-based deposition of $CuIn_xGa_{1-x}Se_2$ (CIGSe) thin films is well known non-vacuum process for the fabrication of CIGSe solar cells. However, due to the usage of organic chemicals in the preparation of CIG precursor solutions, the crystallization of the polycrystalline CIGSe and the performance of CIGSe thin film solar cells were significantly affected by the carbon residues from the organic chemicals. In this work, we have tried to eliminate the carbon residues in the CIG precursor thin films efficiently by using soft-annealing process. By adjusting soft-annealing temperature, it is possible to control the amount of carbon residues in CIG precursor thin films. The reduction of the carbon residues in CIG precursors by high temperature soft-annealing improves the grain size and morphology of polycrystalline CIGSe thin films, which are also closely related with the electrical properties of CIGSe thin film solar cells.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.93-93
• /
• 2013

In recent years, multifunctional ternary nitride thin films have received extenstive attention due to its versatility in many applications. In particular, noble metal based ternary nitride thin films showed a promising properties in the application of Multifunctional heating resistor films because its good electrical properties and excellent resistance against oxidation and corrosion. In this study, we prepared multifunctional noble metal based ternary nitride thin films by atomic layer deposition (ALD) and plasma-enhanced ALD (PEALD) method. ALD and PEALD techniques were used due to their inherent merits such as a precise composition control and large area uniformity, which is very attractive for preparing multicomponent thin films on large area substrate. Here, we will demonstrate the design concept of multifunctional noble metal based ternary thin films. And, the relationship between microstructural evolution and electrical resistivity in noble metal based ternary thin films will be systemically presented. The useful properties of noble metal based ternary thin films including anti-corrosion and anti-oxidation will be discussed in terms of hybrid functionality.

• Korean Journal of Materials Research
• /
• v.28 no.12
• /
• pp.748-757
• /
• 2018

Inorganic semiconductor compounds, e.g., CIGS and CZTS, are promising materials for thin film solar cells because of their high light absorption coefficient and stability. Research on thin film solar cells using this compound has made remarkable progress in the last two decades. Vacuum-based processes, e.g., co-evaporation and sputtering, are well established to obtain high-efficiency CIGS and/or CZTS thin film solar cells with over 20 % of power conversion. However, because the vacuum-based processes need high cost equipment, they pose technological barriers to producing low-cost and large area photovoltaic cells. Recently, non-vacuum based processes, for example the solution/nanoparticle precursor process, the electrodeposition method, or the polymer-capped precursors process, have been intensively studied to reduce capital expenditure. Lately, over 17 % of energy conversion efficiency has been reported by solution precursors methods in CIGS solar cells. This article reviews the status of non-vacuum techniques that are used to fabricate CIGS and CZTS thin films solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.6
• /
• pp.588-593
• /
• 2023

The advantage of OTFT technology is that large-area circuits can be manufactured on flexible substrates using a low-cost solution process such as inkjet printing. Compared to silicon-based inorganic semiconductor processes, the process temperature is lower and the process time is shorter, so it can be widely applied to fields that do not require high electron mobility. Materials that have utility as electrode materials include carbon that can be solution-processed, transparent carbon thin films, and metallic nanoparticles, etc. are being studied. Recently, a technology has been developed to facilitate charge injection by coating the surface of the Al electrode with solution-processable titanium oxide (TiOx), which can greatly improve the performance of OTFT. In order to commercialize OTFT technology, an appropriate method is to use a complementary circuit with excellent reliability and stability. For this, insulators and channel semiconductors using organic materials must have stability in the air. In this study, carbon-doped Mo (MoC) thin films were fabricated with different graphite target power densities via unbalanced magnetron sputtering (UBM). The influence of graphite target power density on the structural, surface area, physical, and electrical properties of MoC films was investigated. MoC thin films deposited by the unbalanced magnetron sputtering method exhibited a smooth and uniform surface. However, as the graphite target power density increased, the rms surface roughness of the MoC film increased, and the hardness and elastic modulus of the MoC thin film increased. Additionally, as the graphite target power density increased, the resistivity value of the MoC film increased. In the performance of an organic thin film transistor using a MoC gate electrode, the carrier mobility, threshold voltage, and drain current on/off ratio (I_on/I_off) showed 0.15 cm²/V·s, -5.6 V, and 7.5×10⁴, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.4
• /
• pp.286-290
• /
• 2020

The formation of inorganic thin films in low-temperature solution processes is necessary for a wide range of commercial applications of organic electronic devices. Aluminum oxide thin films can be utilized as barrier films that prevent the deterioration of an electronic device due to moisture and oxygen in the air. In addition, they can be used as the gate insulating layers of a thin film transistor. In this study, aluminum oxide thin film were formed using two methods simultaneously, a thermal process and the DUV process, and the properties of the thin films were compared. The result of converting aluminum nitrate hydrate to aluminum oxide through a hybrid process using a thermal treatment and DUV was confirmed by XPS measurements. A film-based a-IGZO TFT was fabricated using the formed inorganic thin film as a gate insulating film to confirm its properties.