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Organic-inorganic hybrid materials for unconventional electronics
하영근 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Recent advances in semiconductor performance afforded by organic π-electron molecules, carbon-based nanomaterials, and metal oxides have been a central scientific and technological research focus over the past decade for flexible and transparent electronics. However, recent advances in semiconductor require corresponding advances in compatible gate dielectric materials, which exhibit excellent electrical properties such as large capacitance, high breakdown strength, low leakage current density, as well as mechanical flexibility with arbitrary substrates. High-k inorganics such as hafnium dioxide (HfO<sub>2</sub>) or zirconium dioxide (ZrO<sub>2</sub>) offer some improvements in device performance, but these materials must be very thick to avoid leakage and are difficult to deposit as smooth films on plastics due to high process temperature. Conventional organic/polymeric materials are readily accessible and solution processable. However, these materials exhibit low capacitances, and the corresponding TFTs operate consequently at relatively high voltages. More recently, to combine the desirable properties of high-k metal oxides and organic dielectric processability and mechanical flexibility, a new approach for fabricating gate dielectrics using self-assembled multilayers has emerged. In this presentation, we introduce novel organic-inorganic hybrid gate dielectrics, fabricated by self-assembled multilayer deposition, and its application with unconventional semiconductors.
김대철,하영근 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
We report on the method for a solution-processed organic-inorganic mixture gate dielectric in pentacene thin film transistors. The purpose of this study is suggesting a simple one step method to make a smooth hydrophobic surface; two steps are not necessarily needed like spincoating of zirconium dioxide layer and surface treatment. Also, this method is possible to process in low-temperature. This thin film possessed a low leakage current density and high capacitance. Manufactured TFTs possessed a on/off ratio of ~10<sup>7</sup> and charge carrier mobility of ~0.28㎠/(Vs).
김용완,하영근 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.3
Advanced electronic materials have attracted great interest for their potential use in flexible, large area, and printable electronic applications. However, fabricating high-performance low-voltage thin-film transistors (TFTs) for those applications with these advanced semiconductors is still challenging because of a lack of dielectric materials which satisfy both the required electrical and physical performance. In this work, we report self-assembled hybrid multilayer gate dielectrics prepared using a facile solution procedure to achieve organic semiconductor and amorphous oxide semiconductor-based thin-film transistors with ultralow operating voltage. These self-assembled hybrid multilayer gate dielectrics were constructed by iterative self assembly of synthesized bifunctional phosphonic acid-based organic molecules and ultrathin high-k hafnium oxide layers. The novel self-assembled hybrid multilayer gate dielectrics exhibit excellent dielectric properties with exceptionally large capacitances (up to 815 nF/ cm2 ) and low-level leakage current densities of < 1.56 × 10-6 A/cm2 , featureless morphology (RMS roughness < 0.24 nm), and thermal stability (up to 300 °C). Consequently, these hybrid gate dielectrics can be incorporated into thin-film transistors with pentacene as p-type organic semiconductors, and with indium oxide as n-type inorganic semiconductors. The resulting TFTs functioned at ultralow voltages (< ± 2 V) and achieved high transistor performances (hole mobility: 0.88 cm2 / V·s, electron mobility: 7.8 cm2 / V·s and on/off current ratio >104 , and threshold voltage: ± 0.5 V).
딥코팅 방법을 활용한 게이트 산화물 유전체 및 반도체 박막의 제조 및 박막트랜지스터 응용
김용완,하영근 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.8
The potential applications of advanced electronic materials in large-area, printable, and flexibleelectronics have generated significant interest. However, creating high-performance, low-voltage thin-filmtransistors (TFTs) for these applications remains difficult due to a lack of advanced gate dielectric andsemiconductor materials that meet both ease-of-fabrication requirements and high electrical performance. Inthis study, we present high-performance gate dielectric thin-films, which were fabricated using a facilesolution-based technique, and then employed to realize low operating voltage organic and metal oxidesemiconductor-based thin-film transistors. The high-k oxide gate dielectrics were produced via a simple dipcoatingmethod, resulting in the formation of thin-oxide layers. These novel oxide gate dielectricsdemonstrated exceptional dielectric properties, with large capacitances (up to 430 nF/ cm2), low-level leakagecurrent densities (< 3 × 10-8A/cm2 at 4 V), featureless morphology (rms roughness < 0.36 nm), and hightransparency (> 85%). Consequently, these dip-coated gate dielectrics can be incorporated into thin-filmtransistors, utilizing pentacene as p-type organic semiconductors. Furthermore, by employing dip-coating,indium oxide and indium-gallium-zinc oxide can be utilized as n-type inorganic semiconductors, allowing forthe fabrication of low-voltage operation and high-performance inorganic TFTs. The resulting TFTs functionedat ultralow voltages (< ± 2 V) and achieved high transistor performance (hole mobility: 0.28 cm2V-1·s-1, electronmobility: ~2.0 cm2V-1·s-1 and on/off current ratio >105).
변혜란,하영근 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.7
We report here on the design, processing, and dielectric properties of low surface energy organic/inorganic hybrid dielectric films for low-voltage operation of organic thin-film transistors (OTFTs). The hydrophobic hybrid dielectric films are easily fabricated by one-step spin coating of a zirconium chloride precursor in an octadecyltrimethoxysilane solution under ambient conditions, followed by thermal curing at low temperatures (approximately 150°C). These novel dielectrics exhibit excellent surface smoothness (root-mean-square roughness is <0.5 nm), great insulating property (leakage current densities <10?6 A/cm2), and high capacitance (365?nF/cm2). In addition, the surface nature of the hybrid dielectric is hydrophobic (water contact angle is 105°), without any further surface modifications, which is highly compatible with organic semiconductors. Consequently, the hybrid dielectrics integrated into the pentacene OTFTs function at relatively low voltages (< ?2.5 V) with excellent TFT characteristics (mobility: 0.31?cm2/V·s, on/off current ratio: 105, low threshold voltage: down to ?0.7 V).